Tissue surface treatment apparatus and method

ABSTRACT

A method of controlling ablation volume depth includes providing a treatment apparatus. The apparatus comprises a housing having a proximal and distal end including a tissue contacting surface. The housing defines an interior with an energy delivery device positionable in the interior. The energy delivery device includes at least one electrode with a tissue penetrating distal end and is configured to be advanced from the interior into a target tissue site to define an ablation volume. An advancement device is coupled to the energy delivery device and is configured to advance the at least one electrode. The at least one electrode is advanced to a selected deployment depth beneath a tissue surface while avoiding a critical structure. Energy is delivered from the energy delivery device. An ablation volume is created at a controlled depth below the tissue surface responsive to the deployment depth while minimizing injury to the critical structure.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/797,409entitled, “Tissue Surface Treatment Apparatus And Method”, filed Feb.28, 2001 (now abandoned) which is fully incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to an apparatus and method for theminimally invasive treatment and ablation of tissue masses such astumors, and more particularly to a tissue surface treatment apparatuswith independently deployable electrodes configured to controllablyablate a tumor proximate or beneath a tissue surface.

2. Description of the Related Art

Standard surgical procedure, such as resection, for treating benign andmalignant tumors of the liver and other organs have several keyshortcomings affecting efficacy, morbidity and mortality. In an effortto fully remove or resect the tumor, the surgeon may be forced to removeor injure healthy tissue, compromising the function of the target organ.Further, the surgeon must exercise care in not cutting the tumor in amanner that creates seeding of the tumor, resulting in metastasis andspread of the disease. Also surgical resection procedures arecontraindicated for instances of diffuse disease and/or small amounts ofremaining healthy tissue.

Ablative treatment methods such as radio-frequency ablation,cryoablation, and microwave ablation have been employed as analternative to resection to treat benign and malignant tumors in organssuch as the prostate. However, these therapies in their present formhave several critical drawbacks including: (i) inability toablate/necrose the entire tumor; (ii) inability to ablate or necrosetissue along the entire length/perimeter of the tumor margin; (iii)inability to reduce lesion size sufficiently to reduce pain levels; (iv)inability to treat smaller tumors without potentially damagingsurrounding healthy tissue and/or critical organs and structures; (v)inability of introducer to deploy device at an angle or otherwise accessdifficult to reach tumors; and (vi) inability to determine a meaningfulclinical endpoint

In particular tumors lying near or underneath an organ surface present adistinct set of problems to current ablative therapies. In order tosuperficially treat these type of tumors it is desirable for thephysician to be able to deliver ablative treatment into the tumor, whileavoiding all together or minimizing injury to critical anatomicalstructures that are adjacent and/or underneath the target tumor mass.

SUMMARY OF THE INVENTION

An embodiment provides a method of controlling ablation volume depthduring surface treatment of a target tissue site. The method includesproviding a tissue surface treatment apparatus. The apparatus comprisesa housing having a proximal end and a distal end including a tissuecontacting surface having an aperture. The housing defines an interiorwith an energy delivery device positionable in the housing interior. Theenergy delivery device includes at least one electrode with a tissuepenetrating distal end. The at least one electrode is configured to beadvanced from the housing interior through the aperture and into atarget tissue site to define an ablation volume at least partly boundedby the tissue surface. An advancement device is coupled to the energydelivery device. The advancement device is configured to advance the atleast one electrode from the housing interior to a selected deploymentdepth. The tissue contact surface is positioned on a target tissuesurface. The at least one electrode is advanced to a selected deploymentdepth beneath a tissue surface while avoiding a critical structure.Ablative energy is then delivered from the energy delivery device. Anablation volume is then created at a controlled depth below the tissuesurface responsive to the electrode deployment depth while minimizinginjury to the critical structure.

Another embodiment of the invention provides a tissue surface treatmentapparatus that includes a housing having a proximal end, a distal endincluding a tissue contacting surface and an interior defined by thehousing. A handpiece is coupled to the housing. The tissue contactsurface has a plurality of apertures. An energy delivery deviceincluding at least one electrode is positionable in the housinginterior. The at least one electrode includes a tissue penetratingdistal end in substantial alignment with an aperture of the plurality ofapertures. The at least one electrode is configured to be advanced fromthe housing interior through the aperture and into a target tissue siteto define an ablation volume at least partly bounded by the tissuesurface. An advancement device is coupled to the energy delivery device.The advancement device is at least partly positionable within at leastone of the housing or the handpiece. The advancement device isconfigured to advance the at least one electrode from the housinginterior into the target tissue site and completely withdraw the atleast one electrode into the housing interior. A cable is coupled to oneof the housing or the energy delivery device. The cable is configured tobe coupled to an energy source.

Still another embodiment of the invention includes a switching devicecoupled to at least one of the at least one electrode, a power supplycoupled to the at least one electrode or a ground pad electrode coupledto the power supply. Impedance measurement circuitry is coupled to atleast one of the at least one electrode or the ground pad electrode.Logic resources are coupled to at least one of the impedance measurementcircuitry or the switching device. The logic resources are configured toredirect at least a portion of a current flow going to the ground padelectrode responsive to an impedance change measured by the impedancemeasurement circuitry.

In yet another embodiment, the energy delivery device includes a firstelectrode and a second electrode. The first electrode is deployable to afirst depth and a second electrode is deployable to a second depthindependent of the first depth.

In still yet another embodiment, the handpiece includes a bendable or acurved portion. The bendable portion facilities access by the physicianto difficult to reach areas of the liver such as a posterior portion ora portion adjacent or touching another anatomical structure.

In still another embodiment, the surface treatment apparatus includes afirst RF electrode, a second RF electrode and a third RF electrode. Eachof the first, second and third RF electrodes have a tissue piercingdistal end and are positionable in the housing. The first and second RFelectrodes are selectably deployable with curvature from the housing toa tissue site. The third RF electrode is deployable from the introducerwith less curvature than the first and second RF electrodes.

Still yet another embodiment of the invention provides a tissue surfacetreatment apparatus that includes a housing having a proximal end, adistal end including a tissue contacting surface and interior defined bythe housing. A handpiece is coupled to the housing. A fluid deliverydevice is positionable in the housing interior. The fluid deliverydevice includes at least one hollow non-conducting infusion member withat least one infusion aperture and a tissue penetrating distal end. Theat least one infusion member is configured to be advanced from thehousing interior and into a target tissue site to infuse a fluid intotissue and define a tissue infusion volume. The fluid delivery device isconfigured to be coupled to a fluid source. An advancement device iscoupled to the fluid delivery device. The advancement device is at leastpartly positionable within at least one of the housing or the handpiece.The advancement device is configured to advance at least a portion ofthe at least one infusion member from the housing interior into thetarget tissue site and completely withdraw the at least one infusionmember into the housing interior. A conductor is coupled to at least oneof the fluid delivery device or the at least one infusion member. Theconductor is configured to be coupled to an energy source.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a lateral view illustrating the placement of a surfacetreatment apparatus to treat a tissue mass at or beneath a tissuesurface in an embodiment of the method of the present invention.

FIG. 2 is a lateral view illustrating the components of an embodiment ofa surface treatment apparatus including the housing, tissue contactingsurface, energy delivery device and advancement member.

FIG. 3 is a lateral view illustrating an embodiment of the housing.

FIGS. 4 a-4 e are lateral views illustrating embodiments of the housinghaving various coatings.

FIGS. 5 a-5 e are lateral views of the tissue-contacting surfaceillustrating various contours of the surface as well as the shape of thesurface edge including radiused and curved edges

FIG. 6 is lateral view illustrating placement and use of an embodimentof the invention having a conformable tissue surface.

FIGS. 7 a and 7 b are perspective views illustrating an embodiment of amovable tissue contacting surface.

FIG. 8 is a lateral view illustrating an embodiment of a bendable tissuecontacting surface with hinged sections.

FIGS. 9 a-9 b are bottom surface views illustrating an embodiment of abendable tissue contacting surface with articulated sections.

FIG. 10 is a lateral view illustrating an embodiment of a porous tissuecontacting surface including delivery of a fluid film.

FIG. 11 is a lateral view illustrating an embodiment of a porous tissuecontacting surface including a flexible lip.

FIGS. 12 a and 12 b are lateral views illustrating use of an inflatableporous tissue contacting surface.

FIGS. 13 a and 13 b are lateral views illustrating use of a vacuumsource coupled to porous tissue contacting surface.

FIG. 14 is a lateral view illustrating the angle of an aperturepositioned in the housing for purposes of electrode advancement in anembodiment of the invention.

FIGS. 15 a-15 d are lateral views illustrating various alignments forthe aperture and electrodes of the embodiment in FIG. 7.

FIG. 16 is a lateral view illustrating the configuration and use of anembodiment of a disk-shaped advancement member.

FIG. 17 is a lateral view of an embodiment of a disk-shaped advancementmember integral to the housing.

FIG. 18 is a cross sectional view illustrating the placement ofelectrodes with the advancement member.

FIG. 19 is a cross sectional view illustrating the use of a printedcircuit board in the advancement member.

FIG. 20 a is a lateral view illustrating an embodiment utilizing a pushrod to advance the advancement member as well as the use of springs forretracting the advancement member.

FIG. 20 b is a lateral view illustrating an embodiment utilizing aservomotor or solenoid to advance the advancing the advancement member.

FIG. 20 c is a lateral view illustrating an embodiment utilizingpneumatic means to advance the advancing the advancement member as wellas the use of vacuum source.

FIG. 20 d is a lateral view illustrating an embodiment utilizing aninflatable balloon to advance the advancing the advancement member.

FIG. 21 is a lateral view illustrating an embodiment of an advancementmember comprising one or more pushable advancement members with coupledelectrodes.

FIGS. 22 a-22 e are perspective views illustrating the use of theembodiment of the apparatus of FIG. 13.

FIG. 22 e is a lateral view illustrating an embodiment wherein theadvancement member includes a cam to advance the advancement member.

FIGS. 23 a-23 h are lateral views illustrating various configurations ofthe electrode including ring-like, ball, hemispherical, cylindrical,conical and needle-like.

FIG. 24 is lateral view illustrating an embodiment of a needle electrodeconfigured to penetrate tissue.

FIG. 25 is lateral view illustrating a needle electrode having at leastone radii of curvature.

FIG. 26 is a perspective view of a surface treatment apparatus thatincludes insulation sleeves positioned at exterior surfaces of theelectrodes so as to define an energy delivery surface.

FIG. 27 is a perspective view of a surface treatment apparatus of thepresent invention that includes multiple insulation sleeves thatcircumferentially insulate selected sections of the electrodes.

FIG. 28 is a perspective view of a surface treatment apparatus of thepresent invention with insulation that extends along longitudinalsections of the electrodes to define adjacent longitudinal energydelivery surfaces.

FIG. 29 is a cross-sectional view of the surface treatment apparatus ofFIG. 28.

FIG. 30 a is a lateral view illustrating an embodiment of the apparatuswith an electrode having a lumen and apertures configured for thedelivery of fluid and the use of infused fluid to create an enhancedelectrode.

FIG. 30 b is a lateral view illustrating of embodiment of the apparatusconfigured for the delivery of cooling solution to the electrode andsurrounding tissue.

FIG. 31 is a lateral view illustrating an embodiment of a surfacetreatment apparatus including a handpiece.

FIG. 32 a is a lateral view illustrating an embodiment of the handpiececonfigured to be coupled to fluid delivery and aspirating devices.

FIG. 32 b is a lateral view illustrating an embodiment of the handpieceincluding a positioning fixture and/or a template for control of thedeployment of electrodes into tissue.

FIG. 33 is a lateral view illustrating an embodiment of the handpieceincluding a curved portion.

FIG. 34 is a lateral view illustrating an embodiment of the handpieceincluding a bendable portion.

FIG. 35 is a lateral view illustrating an embodiment of a surfacetreatment apparatus having a handpiece configured to controllablymanipulate the tissue contact surface.

FIGS. 36 a and 36 b are lateral views illustrating an embodiment of thesurface treatment apparatus with electrodes in a non-deployed anddeployed state.

FIG. 37 is a lateral view illustrating an embodiment of the surfacetreatment apparatus having an array of electrodes.

FIG. 38 a is a perspective view illustrating an embodiment having arectangular array of electrodes

FIG. 38 b is a lateral view illustrating the spacing between electroderows for the embodiment of FIG. 38 a.

FIG. 39 is a lateral view illustrating an embodiment of the housinghaving a stop configured to control electrode penetration depth.

FIG. 40 is a lateral view illustrating an embodiment of the housinghaving a movably adjustable stop.

FIG. 41 is a schematic view illustrating an embodiment of the apparatushaving multiplexed electrodes configured to produce spatial and temporalpatterns of energy delivery.

FIG. 42 is a schematic view illustrating an embodiment of the powersupply having multiple independent channels to each electrode.

FIG. 43 is a schematic view illustrating use of a ground pad electrodefor monopolar embodiments of the invention.

FIGS. 44 a-44 c are schematic views illustrating configurations of theelectrodes in bipolar embodiments of the invention. FIG. 44 a shows anembodiment with a single positive and negative electrode. FIG. 44 bshows multiple positive electrodes in a circular pattern with acentrally located return electrode. FIG. 44 c shows an arc shapedpattern of positive electrodes with a single return electrode.

FIG. 45 is a schematic view illustrating an embodiment of tissue contactsurface having a conductive tissue portion employed in monopolar andbipolar modes.

FIG. 46 is a schematic view illustrating an embodiment of the tissuecontact surface having multiple conductive portions.

FIG. 47 is a schematic view illustrating an embodiment of a conductivetissue contact surface used to generate and control a current/energyvector within the target tissue volume.

FIG. 48 is a schematic view illustrating an embodiment of the surfacetreatment apparatus having a phased array of electrodes.

FIG. 49 a is a flow chart illustrating an embodiment of a method of theinvention utilizing an algorithm to switch between monopolar and bipolarmodes based on measurement of tissue impedance.

FIG. 49 b is schematic view of an embodiment of an apparatus forperforming the method of FIG. 49 a.

FIGS. 50 a and 50 b are lateral views illustrating embodiments of acollapsible strut surface treatment apparatus in a non-deployed anddeployed state having a fixed distal hub.

FIG. 51 is a lateral view illustrating an alternative embodiment of thecollapsible strut surface treatment apparatus having a movable distalhub.

FIG. 52 is a lateral view illustrating the use of the embodiment of FIG.50 b or FIG. 51 to produce multiple ablation volumes.

FIG. 53 a is a lateral view illustrating an embodiment of a collapsiblesurface treatment apparatus utilizing an expandable balloon device.

FIG. 53 b is a lateral view illustrating an embodiment of a collapsiblesurface treatment apparatus utilizing an expandable balloon device witha restraining member.

FIG. 54 is a block diagram illustrating a controller, power source,power circuits and other electronic components used with an embodimentof a control system other embodiments of the invention.

FIG. 55 is a block diagram illustrating an analog amplifier, analogmultiplexer and microprocessor used with an embodiment of a controlsystem other embodiments of the invention.

DETAILED DESCRIPTION

In order to superficially treat organ tumors (e.g. hepatic tumors),particularly those near the tissue surface it is desirable for thephysician to be able to deploy electrodes into the tumor while avoidingand minimizing injury to adjacent critical anatomical structures thatare adjacent and underneath the target tumor mass.

The present invention provides an apparatus and method to address thisand other need in performing surface treatment of tissue masses andtumors such as liver tumors using both open chest procedures andminimally invasive procedures. In particular, embodiments of theinvention are configured to selectively deploy individual electrodes oran array of electrodes into a tumor or tissue mass so as to achieve aparticular pattern to precisely treat the tumor while avoiding adjacentcritical anatomical structures such as vasculature (e.g. hepatic veins)and nerve plexi. Further, the apparatus of the present invention allowsthe electrodes to be deployed to a selective depth again to solve theproblem of deploying electrodes into the tumor mass while avoidingdeeper healthy tissue. In a preferred embodiment, the electrodes aredeployable to a depth of 1.5 cm.

Also, various embodiments are configured to treat not only accessibleanterior portions of the liver but also posterior portions and/orportions obstructed by overlying or adjacent tissue and other organs andtissue. This capability is achieved through the use of components withsufficient flexibility and resiliency to bend, curve around or conformto tissue and anatomical structures including organs, bone andvasculature. Components of the apparatus of the invention having thisflexibility can include the handpiece, housing and tissue contactsurface described in detail herein. This flexibility enables theapparatus to not only be readily manipulated and positioned in at leastpartially obstructed tissue but also to deliver energy, fluids and applypressure to and on obstructed or otherwise difficult to reach targettissue sites.

Referring to FIGS. 1 and 2, FIG. 1 shows an embodiment of surfacetreatment apparatus 10 to superficially treat a tumor mass 5″ in atarget tissue site 5′ at or beneath the surface 5 s of tissue 5 bydelivering energy to produce an ablation volume 5 av. As shown in FIG. 2apparatus 10 includes a housing 12 that has a proximal and distalportion 12 p and 12 d and an interior space 12 i. All or a portion ofhousing 12 can be configured to contact a tissue surface 5 s at a targettissue site 5′. In an embodiment housing 12 includes a tissue contactingsurface 14 positioned at distal portion 12 d. Tissue contacting surface14 can have one or more apertures 14 a. An electrode advancement member16 is positionable within the housing and coupled to one or more energydelivery devices 18. The energy delivery devices 18 can have distal ends18 de sufficiently sharp to penetrate tissue electrodes. Energy deliverydevices 18 are positionable within the housing 12 and configured to beadvanced out of the apertures 14 a into tissue to a target tissue site5′. Energy delivery device 18 can be configured to be coupled to anenergy or power source 20. A sensor 22 may be coupled to energy deliverydevice 18, as well as housing 12 including tissue contacting surface 14.Sensors 22 can be configured to measure temperature, impedance or otherphysical properties of the housing, energy delivery device and adjacenttissue.

A variety of energy delivery devices and power sources can be utilizedby embodiments of the invention. Specific energy delivery devices 18 andpower sources 20 that can be employed in one or more embodimentsinclude, but are not limited to, the following: (i) a microwave powersource coupled to a microwave antenna providing microwave energy in thefrequency range from about 915 MHz to about 2.45 GHz; (ii) aradio-frequency (RF) power source coupled to an RF electrode; (iii) acoherent light source coupled to an optical fiber or light pipe; (iv) anincoherent light source coupled to an optical fiber; (v) a heated fluidcoupled to a catheter with a closed or at least partially open lumenconfigured to receive the heated fluid; (vi) a cooled fluid coupled to acatheter with a closed or at least partially open lumen configured toreceive the cooled fluid; (viii) a cryogenic fluid; (ix) a resistiveheating source coupled to a conductive wire; (x) an ultrasound powersource coupled to an ultrasound emitter, wherein the ultrasound powersource produces ultrasound energy in the range of about 300 KHZ to about3 GHz; and (xi) combinations thereof. For ease of discussion for theremainder of this application, the energy delivery device 18 is one ormore RF electrodes 18 and the power source utilized is an RF powersupply. However all energy devices and sources discussed herein areequally applicable.

Housing 12 can have a variety of shapes including rectangular, circular,oval and pyramidal. Referring to FIG. 3, in a preferred embodimenthousing 12 has a cylindrical shape, where the proximal and distal ends12 p and 12 d comprise the two ends of the cylinder with a wall 12 w.Ends 12 p and 12 d can be fixedly attached to the body of the cylinder12 b or can be movable therein which can include sliding and reciprocalmovement. Housing 12 can be fabricated from a variety of polymers knownin the art including rigid polymers, including but not limited topolycarbonate, acrylic, polyester, ABS and combinations thereof usinginjection molding or rim methods known in the art. Also housing 12 canbe machined from both plastics and metals such as aluminum, stainlesssteel and the like, using machining methods known in the art. Housing 12can also be made from flexible metals such as or from compliant orresilient polymers that enable housing 12 to be flexible in one or moredirections. Examples of flexible metals include, but are not limited to,nickel titanium alloys. Examples of resilient polymers include, but arenot limited to, elastomers including silicone, polyurethane, PEBAX® andcombinations thereof. Flexibility of housing 12 can also be achievedthrough the use of an accordion or bellow construction of housing walls12 w. Also, in an embodiment all or portions of housing 12 can havetransparent portions or viewing ports 12 v made of transparent polymerssuch as polycarbonate so as to enable the physician to observe thetissue contacted by the housing as well as the position and advancementof the energy delivery devices there into. In use, this embodiment notonly allows the physician to observe the tissue during placement of thehousing 12, but also during the delivery of thermal energy to tissuesite 5″ and thus observe tissue blanching and other color changesindicative of the size of the developing ablation volume.

Referring to FIGS. 4 a-4 e, in various embodiments all or a portion ofhousing 12, including tissue contacting surface 14 can have a coating 12c which can be an insulative coating 12 ic, an electrical conductivecoating 12 ec, a lubricous coatings 12 lc or a thermally reflectivecoating 12 tr. These and other coatings can be applied using dipcoating, spray coating, electro-deposition, plasma coating, lithographicand other coating methods known in the art.

For purposes of this application, an insulative coating is defined to beboth an electrical and a thermal insulative coating. In a preferredembodiment, tissue contact surface 14 has an insulative coating 12 icthat insulates against the transmission of RF energy. Coating 12 ic canbe made from electrically and thermally insulative polymers known in theart including, but not limited to, polyamide, polyamide fluorocarbons,PTFE and TEFLON®. Such coatings can range in thickness 12 ct from 0.0001to 0.1 inches with a preferred embodiment of 0.001 to 0.003 inches. Alsoin an embodiment, coating 12 ic can be a peelable coating so as to bedetachable or movable on housing 12, enabling the user to create aselectable insulative portion 12 ip. Coating 12 ic can be configured tobe peelable and re-attachable using re-attachable, low strengthadhesives known in the art.

In a related embodiment, coating 12 c can be a non-stick or lubricouscoating 12 lc configured to keep surface 14 or other portion of housing12 or energy delivery 18 from sticking to tissue surface 5 s beforeduring or after ablation. This solves the problem of coagulated or burnttissue undesirably sticking to surface 14 preventing its removal and/orcausing unwanted tearing and other trauma to tissue surface 5 s ortissue 5. Such coatings can include PTFE, TEFLON and other fluoro-carbonpolymers, silicones, paralene and other low surface tension non-stickcoatings known in the art.

In another embodiment, coating 12 c can be a thermally reflectivecoating 12 trc. Examples of thermal reflective coating include metalcoatings such as aluminum coating, silver coating, alloys thereof andthe like. In use thermal reflective coating 12 trc on contact surface 14serves to reflect radiated heat back into the tissue surface at thetarget site 5′ and thereby increase the rate of heating of the tissuesite 5′ including tissue mass 5″ resulting in faster and larger ablationvolumes with less delivered power.

In still another embodiment coating 12 c can be a textured coating 12 tcconfigured to increase the coefficient of friction with tissue surface 5s. In use, this serves to stabilize contact surface 14 on tissue surface5 s and/or reduce movement of contact surface. Suitable coatings andpatterns can include high friction polyurethane-polyether or polyesterpolymer coatings carbide coatings, knurled and diamond pattern coatingsand the like known in the art.

Turning now to a discussion of the tissue contacting surface 14 (alsocalled tissue contact surface 14), this component can have a variety ofshapes including but not limited to circular, oval, rectangular, squareand combinations thereof. Referring now to FIGS. 5 a to 5 e, contactsurface 14 can have a variety of contours 14 ctr including curvedcontours including convex or concave curved contours and combinationsthereof. Additionally, the edges 14 e of contacting portion 14 can betapered 14 t or radiused 14 r.

Referring to FIG. 6, in various embodiments all or a portion of thetissue contact surface 14 can be a conformable surface 14 c thatconforms or bends to the shape of tissue surface 5 s. This can beaccomplished by constructing all or a portion of surface 14 fromresilient polymers including but not limited to elastomers such assilicone and polyurethane and polymers thereof as wells as foam rubber.Surface 14 c can be fabricated from such materials using injectionmolding or mandrel dip coating methods known in the art.

In use, a conformable or movable surface solves the problem of assuringand maintaining contact with an uneven or obstructed tissue surfacebefore, during or after the ablation without causing undesired tissuetrauma. In a related embodiment, a conformable surface 14 c can also becoupled to a deflecting mechanism described herein to allow thephysician to remotely deflect or shape contact surface 14 to a shapethat at least partially matches that of a selected target tissue surface5 s or otherwise facilitates positioning of surface 14 on target tissuesurface 5 s. This embodiment solves the problem of allowing thephysician to position surface 14 when the target tissue surface 5 s isobstructed by tissue and anatomical structures or is otherwise in adifficult position to reach.

Referring to FIGS. 7 a and 7 b, in another embodiment the tissuecontacting surface 14 is movable (longitudinally or otherwise) inresponse to force applied by the tissue surface onto the tissue surface14. This can be achieved through a variety of known spring mechanismsincluding constructing surface 14 on a movable cylinder or sleeve 14 mswhich can travel under or over housing 12 and then positioning andcoupling one or more compressed coiled springs 14 sprg to and betweenthe surface 14 and housing 12. This embodiment solves the problem ofassuring and maintaining contact with the tissue surface before, duringor after the ablation without causing undesired tissue trauma due to theapplication of excessive force to the tissue.

Referring to FIGS. 8 and 9 a-9 b, in other embodiments surface 14 cancomprise one or more bendable sections 14 b. In an embodiment shown inFIG. 8, bendable sections 14 b can include hinges 14 h′ to allow surface14 to be moved and shaped by the physician prior to or duringapplication of surface 14 to the target tissue surface. The hinges 14 h′used can include those known in the art including spring loaded hingesgiving the bendable sections 14 b shape resilience. Hinges 14′ can alsoinclude bearings, roller bearings, and miniature bearings such as thosemanufactured by RMB Miniature Bearings (Biel-Bienne, Switzerland). In arelated embodiment shown in FIGS. 9 a-9 b, all or portion of surface 14can include articulated sections 14 as fabricated using known methods ofarticulated construction such as use of corrugated sections made usingmolding methods known in the art. Articulated sections 14 as have asufficient number of articulations 14 as′ to allow robust movement ofsurface 14 in one or more directions. Articulated sections 14 as can beconfigured to bend or deflect with a selectable amount of applied forcewhich can be in the range of 0.01 to 2 lbs with specific embodiment of0.05, 0.1, 0.25, 0.5 and 1 lb of force.

Referring to FIGS. 10-14, in various embodiments, all or a portion ofconformable surface 14 can be constructed from a porous material fluidlycoupled to a fluid source and/or fluid delivery device described herein.In an embodiment shown in FIG. 10, a porous portion or section 14 p ofsurface 14 is configured to deliver a fluid film 14 ff to target tissuesurface 5 s. Porous portion 14 p can be made from a porous membrane orother porous material. Suitable porous materials can include but are notlimited to foam, foam rubber, polyurethane foam, cellulose and woven orknitted DACRON, knitted polyester, continuous filament polyester,polyester-cellulose, rayon, polyamide, polyurethane, polyethylene andthe like. The delivery of a fluid film in this manner can be configuredto perform one or more of the following functions: (i) produce a virtualfluid electrode adjacent or in the tissue surface to uniformly deliverRF energy to the selected tissue surface and underlying tissue whenusing a conductive solution; (ii) produce a virtual and electricallyuniform ground pad electrode on the selected tissue surface to act as areturn path for RF energy when using a conductive solution; and (iii)provide cooling over the selected tissue surface when a cooling solutionis used which can also be a conductive solution. Porous surface 14 p canhave selectable and/or variable amounts of porosity. In one embodiment,porous portion 14 p has uniform porosity and thickness so as to be ableto achieve a substantially uniform delivery of fluid over porous portionsurface 14 ps. In another embodiment the porosity is varied over portion14 p including surface 14 ps to produce varying amounts of fluid flow.For example, higher porosity on the perimeter to produce greater flowson the perimeter or edges of section 14 p or alternatively greaterporosities in the center portion. Also the porosity of section 14 p canbe controlled to retain fluid within the interior of section 14 p inorder to have section 14 p act as a virtual or enhanced electrode 40(described here in) including a virtual flexible electrode.Alternatively, one or more RF electrodes, such as plate or ring shapedRF electrodes 18, may be positioned within section 14 p to both cool theelectrode and conduct RF energy to section 14 p to allow section 14 p toact as an RF electrode to deliver RF energy to tissue surface 5 s andunderlying tissue.

As shown in FIG. 11, porous section 14 p can include a flexible lip orgasket section 14 pg to trap or otherwise contain the fluid film betweencontact surface 14 and tissue surface 5 s. Gasket section 14 pg can bemade out of resilient polymers including elastomers such as silicone andcan be located anywhere along surface 14 including all or a portion ofthe perimeter 14 pmt of contact surface 14.

As shown in FIGS. 12 a and 12 b, in related embodiments the porosity ofporous portions 14 p can be used to control the flexibility stiffness ofsurface 14 by retaining greater or lesser amounts of fluid withinsection 14 p to control its hydrostatic pressure (when the surface iscoupled to a pressurized fluid delivery device such as an IV pump) andeffectively inflate or deflate the section 14 p (similar to aninflatable balloon) to a desired stiffness and shape. This can also bedone by controlling the fluid pressure of the fluid delivery device 28or fluid source 30 coupled to porous section 14 p.

As shown in FIGS. 13 a and 13 b, in another embodiment porous portion 14p can also be configured to deliver a vacuum to between tissue contactsurface 14 s and tissue surface 5 s. This can be achieved by couplingportion 14 p and apparatus 10 to a vacuum source 30 v known in themedical equipment art. The generation of a vacuum at tissue contactsurface 14 via portion 14 p or other means can provide one or more ofthe following benefits: (i) rapidly get all or portions of contactsurface 14 s to conform to the shape of tissue 5 s, which isparticularly beneficial when access to apparatus 10 and tissue surface14 is limited or obstructed (e.g. when surface 14 is placed on theposterior side or otherwise underneath the liver); and (ii) providesufficient vacuum to stabilize or even fixedly attached contact surface14 onto tissue surface 5 s to prevent undesired movement of housing 12and surface 14 during electrode deployment, respiration, involuntarymuscle contraction, or inadvertent jarring during the medical procedure.

Referring to FIG. 14, apertures 14 a in surface 14 can be configured tohave a selectable angle, 14 aa with respect to a longitudinal plane 14lp of tissue contact surface 14 such that electrode 18 exits theaperture and enters into tissue at that angle. Angle 14 aa can be in therange of 1 to 180° with specific embodiments of 30, 45, 60, 90, 120 and135°.

Referring to FIGS. 15 a-15 d, in various embodiments aperture 14 a andelectrode 18 can have different alignments including but not limited tothe following: (i) aperture locus 14 ac aligned with the centerline axis18 acl of electrode 18; (ii) aperture longitudinal axis 14 aalsubstantially aligned with the electrode longitudinal axis 18 al; and(iii) electrode longitudinal axis 18 al substantially perpendicular toaperture plane 14 ap.

In addition to apertures 14 a, in various embodiments tissue contactsurface 14, including housing 12, can include one or more tissue accessports 14 tp that are distributed in one or more locations in surface 14.Access ports can have sufficient diameter to allow access by varioussurgical instruments including trocars, scalpels, hemostats, biopsyneedles and surgical scissors. The diameter of port 14 p can range from0.1 to 1″ with specific embodiments of 0.25, 0.5 and 0.75 inches. Alsoaccess port 14 p can be covered with transparent covers. In use accessports 14 p are configured to allow the physician access to tissuesurface 5 p and underlying tissue to in order to obtain biopsies, insertcatheter devices, do resections and other surgical procedures. Accessports 14 p can also be configured to provide an anchoring function forcontact surface 14 and housing 12. To this end, access ports 14 p caninclude or coupled to an anchoring member 14 am which extends from theaccess port to a selectable depth in tissue. Anchoring member 14 am canhave a sharpened distal tip which can be a trocar or other needle shapeknown in the art or described herein. In use anchoring member serves tostabilize and anchor housing 12 and tissue contact surface 14 to tissuesurface 5 s. In an embodiment, anchoring member 14 am can have a helicalor corkscrew shape which can be screwed into tissue. In a relatedembodiment, one or more electrodes 18 can also have a helical shape toprovide an anchoring function as well.

Turning now to a discussion of advancement member 16, this component isconfigured to controllably advance energy electrodes 18 from theinterior 12 i of housing 12 into tissue at the target tissue site.Advancement member 16 can be freely moving within the interior ofhousing 12 with movement including reciprocal linear motion, axialmotion, lateral motions, rotary motion and combinations thereof.Advancement member 16 can also be at least partially positionable in ahandpiece (described herein) coupled to housing 12.

In an embodiment shown in FIG. 16, advancement member 16 comprises adisk parallel to proximal or distal end 12 p or 12 d, coupled orattached to one or more electrodes 18 that preferably have anlongitudinal axis 18 al perpendicular to the surface 16 s of advancementdevice 16. Disk 16 can be configured to move within housing interior 12i in a reciprocal fashion with respect to the longitudinal axis 12 al ofhousing 12. The movement can be slidable, rotational or a combinationthereof. This is achieved by selecting the outer disk 16 od to beslightly less than the internal housing diameter 12 id. The resultinggap 12 g between the two can be in the range of 0.001 to 0.010 withpreferred embodiments of 0.003 and 0.005 inches. Motion between the twocan also be facilitate by use of a lubricous coating 12 c or 16 s on oneor both of the contacting surfaces of housing 12 or disk 16.Alternatively a sleeve bearing or insert 12 sb can be placed within thecontact surface of housing interior 12 i. Sleeve bearing 12 sb can haveshape and materials known in the art.

In an embodiment shown in FIG. 17, member 16 which can be disk shaped oranother shape, can comprise all or a portion of proximal end 12 p ofhousing 12, thus making proximal end 12 p movably coupled to housinginterior 12 i. In this and related embodiments, movable proximal end 12p can be configured to move or slide reciprocally within in housing 12.

Referring to FIG. 18, electrodes 18 can be positioned in holes 16 hformed or drilled in disk surface 16 s and then subsequently adhered inplace using adhesive known in the art including but not limited tomedical grade including medical grade adhesives such as medical gradeepoxies. Also the fit between electrode 18 and hold 16 h can be aninterference fit or within 0.001 to 0.005 of an inch. Hole 16 h can be athrough or a blind hole. Preferably hole 16 h has a proximal opening 16hp to allow a wire 18 h to be electrically coupled (e.g. by soldering)to each electrode. Wire 18 h either then is coupled directly to powersource 20 or to a cable 20 c electronically coupled to power source 20.

In an alternative embodiment shown in FIG. 19, electrodes 18 can becoupled to a printed circuit board 17 (using a solder joint or pincoupling), which can be a flex circuit, positioned on the surface 16 s(proximal or distal) or the interior of disk 16. Circuit board 17 caninclude a connector 17 c such as a tab, pin, blade or mechanicalconnector known in the art, to connect to electrodes 18. Also circuitboard 17 can include integral multiplexing or switching circuitry 46 aswell as impedance and temperature sensors 22. In another alternativeembodiment, the proximal portions of electrodes 18 extend all the waythrough holes 16 h to the proximal side of disk member 16 and arecoupled to wires 18 h outside of the disk.

In an embodiment shown in FIG. 21, advancement member 16 comprises oneor more individual pushable advancement members 19 each coupled to orincluding an individual electrode 18 that is aligned with acorresponding apertures 14 a so as to exit from aperture 14 a. Pushableadvancement members 19 can in turn be configured to be mechanicallyadvanced by means of an advancement tool 21 that is configured to beinserted through a proximal aperture 12 pa that is aligned withadvancement member longitudinal axis 19 al.

Pushable member 19 has proximal and a distal portion 19 p and 19 d.Proximal portion 19 p can have an inward convex curve 19 c orindentation 19 i to facilitate force application and advancement bypushing tool 21. Similarly the advancements tool 21 can have a recessedor convex curved contour 21 c at its proximal portion to facilitatefinger manipulation. At least a portion of distal portion 19 d compriseelectrode 18. The proximal portion can have a significantly largerdiameter 19 dp relative to distal portion rendering proximal portionstiffer than distal portion. The ratio of diameters of proximal todistal portion can be in the range of 1:2 to 1:10, with correspondingratios of column strength or stiffness. Proximal portion 19 p hassufficient diameter and column strength to advance the entire length ofelectrode 18 into various tissue include hard fibrous tissue such.Proximal portion 19 p can have a diameter in the range of 0.1 to 0.5inches with specific embodiment of 0.2, 0.3 and 0.4 inches. The proximalportion 19 p can be made of a conductive high strength metal such as 304or 304V stainless steel or hardened tool steel. Proximal portion 19 pand distal portion 19 d can be an integral component or can be joinedusing metal working methods known in the art including soldering,brazing and welding. Advancement member 19 can be configured to beretracted by means of a spring such as a coiled spring 19 g that can bepositioned over distal portion 19 p or otherwise coupled to advancementmember 19. Spring 19 g has diameter 19 gd configured to fit over distalportion 19 d/electrode 18 but be contained or but up against the largerdiameter of proximal portion 19 p. A releasable locking or clamp device19 cd can be coupled to spring 19 g and advancement member to be ablelock advancement member 19 and electrode position deployed. Advancementtool 21 has a proximal portion 21 p and elongated portion 21 e,including a distal portion 21 d. Proximal portion can have a cylindricalshape configured to held and pushed with finger including a recessedproximal contour 21 cp. Also all or portions of tool 21 can including aproximal portion 21 p can be include an electrically insulative layer 21c to electrically isolate tool 21 from member 19. Elongated portion 21 ecan be a solid cylindrical shaft configured to be inserted throughproximal aperture 12 pa and make contact with and advance advancementmember 19. Proximal portion 21 p can be configured to remain outside ofthe housing 12 (by virtue of it having a larger diameter than proximalaperture 12 a), such that the length 21 e of elongated portion 21 econtrol the penetration depth 18 pd of electrode 18. Accordingly, thelength 18 el of elongated portion 18 e can be in the range of 0.1 to 5cm with specific embodiment of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 and 4.0 cm.All or portions of tool 21 can be made from rigid injection moldablepolymers such as polycarbonate or ABS or machined tool steel known inthe art. In an embodiment tool can be thumbtack shaped with a plasticproximal portion 12 p and an embedded elongated portion 21 e.

Referring to FIG. 22, in a method of the invention the physician can useone or more advancement members 19 having different elongated sectionlengths 19 e to deploy one or more selected electrodes of electrodearray 18 a to selectable depths to produce a volumetric pattern 5 p orprofile of deployed electrode 18 to correlate to a tumor mass 5″ andavoid nearby critical structures so as to produce a selectable ablationvolume 5 av. The physician could use locking device 19 cd to lock eachelectrode in place during energy delivery and subsequently release oneor more selected electrode and then re-deploy those electrodes to adifferent depth for a second delivery of energy to produce a continuousablation volume or two or more distinct ablation volumes.

Referring to FIGS. 20 a-20 e, advancement member 16 can be advanced by anumber of different mechanical, electromechanical or pneumatic meansknown in the art which can be coupled or integral to advancement member16. In these and related embodiments advancement member 16 can anadvancement device 16 or otherwise include an advancement device. In apreferred embodiment shown in FIG. 20 a, member 16 is advanced by meansof a push rod or stiffened cable 16 c coupled to member surface 16 s anda handpiece 24 actuable by an actuator 24″ on handpiece 24 bothdescribed herein. In this and other embodiments retraction of member 16(e.g. proximal movement) can be achieved through the use of one or moresprings 16 sprg, such as coil spring coupled to the proximal or distalsurface of member 16 and the proximal or distal surface of housinginterior 12 i. When member 16 is advanced in the proximal directionspring 16 sprg is stretched such that the spring now exerts a springforce on member 16 in the proximal direction. When the deployment forceexerted by the push rod, servo motor, air pressure or other meansdescribed herein is removed, the spring force is sufficient to causemember 16 to be withdrawn back to its starting position and withdrawalelectrodes 18 from their deployed state in tissue. In variousembodiments, the spring force of the one or more springs 16 sprg can bein the range of 0.1 to 5 lbs with specific embodiments of 0.25, 0.5,0.75, 1 and 2.5 lbs. Springs 16 sprg can be made from spring steel knownin the art. In one embodiment springs 16 sprgs are configured to have aselectable amount of spring force achieved through the amount ofcompression or deflection of the spring.

In an alternative embodiment shown in FIG. 20 b, member 16 can beadvanced by a servo motor or solenoid 16 m known in the art positionedon the interior or exterior of housing 12 and mechanical coupled tomember 16. Motor 16 m can include miniature motors including the typesused for positioning auto-focus lenses such as those manufactured by RMBMiniature Bearings (Switzerland). Position sensors 22 such as LVDT's canbe positioned on member 16 or housing interior 12 id to provideinformation on the location of member 16 and amount of deployment ofelectrodes 18. In still another embodiment shown in FIG. 20 c, member 16can be advanced by pneumatic means such as a source of compressed air orinert gas and the like 16 g fluidly coupled to housing interior 12 i.Gas 16 g can also be used to cool the housing 12 including surface 14,electrode 18 and tissue surface 5 s. In a related embodiment, member 16and housing interior 12 i are coupled to a vacuum source 16 v configuredto reverse the motion of member 16 and withdrawal coupled electrodes 18.Vacuum source 16 v can also be used to provide suction and adherence ofcontacting surface 14 to tissue surface 14 via the use of one or moresuction apertures 14 va positioned on surface 14. Apertures 14 va can bethe same as 14 a. This solves the problem of achieving and maintaininggood contact between contact surface 14 and tissue surface 5 s (before,during and after energy delivery) as well allowing rapid release betweenthe two. Both compressed gas source 16 g and vacuum 16 c can be actuableby actuator 24″ which can be or otherwise electronically coupled to acontrol valve 24 cv known in the art.

In another embodiment shown in FIG. 20 d, advancement member 16 isadvanced by inflatable balloon device 16 ib positioned within housinginterior 12 i and coupled (movably or attached) to member 16. Inflationof balloon 16 ib exert sufficient force against member surface 16 s(which is opposed by an equal opposite force on housing interior 12 i)so as to push member 16 in a distal direction and deploy electrodes 18.Balloon device 16 ib can be coupled to an inflation/deflation deviceknown in the art or to compressed gas source 16 g and/or vacuum source16 c. In an embodiment balloon device 16 ib can be mechanically coupled,directly attached to or integral with member 16 and housing interior 12i such that the inflation/deflation of balloon 16 ib directly advancesand retracts member 16 so as to deploy and retract electrodes 18.

Balloon device 16 ib can be a balloon catheter or other medical balloondevice known in the art made from balloon materials known in the medicaldevice arts including but not limited to polyester, polyethylene (HDPEincluding radiated HDPE) latex and other non-compliant and compliantballoon materials. Balloon device 16 ib can be fabricated using balloonblowing methods known in the art including the use of mold blownballoons.

Referring to FIG. 20 e, in an embodiment advancement member 16 can be anadvancement device 16 and can comprise a cam 16 c known in the art whosemotion serves to advance energy delivery device 18 through contact ofthe cam surface 16 s with the proximal end 18 p or other portion theenergy delivery device. Suitable cams include disk cams, translationalcams or cylindrical cams configured to operate within housing 12 usingrotary, axial or lateral motion and a suitable cam follower 16 cf whichcan be coupled to energy delivery device 18 or can be energy deliverydevice 18 itself. In another embodiment the advancement device 16 can bemovably or detachably coupled to electrodes 18 including rotational,pivotal and reciprocal couplings.

Turning now to a discussion of electrodes and electrode configurations,in various embodiments electrodes 18 can have a variety of shapes andgeometries. Referring to FIGS. 23 a-23 h, example shapes and geometriescan include, but are not limited to, ring-like, ball, hemispherical,cylindrical, conical, needle-like and combinations thereof. Referring toFIG. 24, in an embodiment electrode 18 can be a needle with sufficientsharpness to penetrate tissue including fibrous tissue including,encapsulated tumors cartilage and bone. The distal end 18 de ofelectrode 18 can have a cut angle 68 that ranges from 1 to 60°, withpreferred ranges of at least 25° or, at least 30° and specificembodiment of 25° and 30°. The surface of electrode 18 can be smooth ortextured and concave or convex. The conductive surface area 18 s ofelectrode 18 can range from 0.05 mm2 to 100 cm2. Referring to FIG. 25,electrode 18 can also be configured to be flexible and or deflectablehaving one or more radii of curvature 70 which can exceed 180° ofcurvature. In use, electrode 18 can be positioned to heat, necrose orablate any selected target tissue volume 5′. A radiopaque marker 11 canbe coated on electrodes 18 for visualization purposes.

Electrode 18 can be made of a variety of conductive materials, bothmetallic and non-metallic. Suitable materials for electrode 18 include,steel such as 304 stainless steel of hypodermic quality, platinum, gold,silver and alloys and combinations thereof. Also, electrode 18 can bemade of conductive solid or hollow straight wires of various shapes suchas round, flat, triangular, rectangular, hexagonal, elliptical and thelike. In a specific embodiment all or portions of electrodes 18 and 18′can be made of a shaped memory metal, such as NiTi, commerciallyavailable from Raychem Corporation, Menlo Park, Calif.

Electrode 18 can be coupled to housing 12, contacting surface 14 oradvancement member 16 using soldering, brazing, welding, crimping,adhesive bonding and other joining methods known in the medical devicearts. Also, electrode 18 can include one or more coupled sensors 22 tomeasure temperature and impedance (both of the electrode and surroundingtissue), voltage and current other physical properties of the electrodeand adjacent tissue. Sensors 22 can be at exterior surfaces ofelectrodes 18 at their distal ends or intermediate sections.

Referring now to FIGS. 26 through 29 in various embodiments one or moreelectrode 18 can be covered by an insulative layer 18 il so as to havean exterior surface that is wholly or partially insulated and provide anon-insulated area which is an energy delivery surface 18 eds. In anembodiment shown in FIG. 26, insulative layer 18 il can comprise asleeve that can be fixed or slidably positioned along the length ofelectrode 18 to vary and control the length of energy delivery surface18 eds. Suitable material for insulative layer 18 il include polyimideand flouro-carbon polymer such as TEFLON.

In the embodiment shown in FIG. 27, insulation 18 il is formed at theexterior of electrodes 18 in circumferential patterns, leaving aplurality of energy delivery surfaces 18 eds. In an embodiment shown inFIGS. 28 and 29, insulation 18 il extends along a longitudinal exteriorsurface of electrodes 18. Insulation 18 il can extend along a selecteddistance along a longitudinal length of electrodes 18 and around aselectable portion of a circumference of electrodes 18. In variousembodiments, sections of electrodes 18 can have insulation 18 il alongselected longitudinal lengths of electrodes 18 as well as completelysurround one or more circumferential sections of electrodes 18.Insulation 18 il positioned at the exterior of electrodes 18 can bevaried to define any desired shape, size and geometry of energy deliverysurface 18 eds. As described herein, insulation layer 18 il can also beapplied to contact surface 14 l including conductive portion 14 con in asimilar variety of sizes and geometries.

Referring now to FIGS. 30 a and 30 b, electrode 18 can include one ormore lumens 72 (which can be contiguous with or the same as lumen 13)coupled to a plurality of fluid distribution ports 23 (which can beapertures 23) from which a variety of fluids 27 can be introduced,including conductivity enhancing fluids, electrolytic solutions, salinesolutions, cooling fluids, cryogenic fluids, gases, chemotherapeuticagents, medicaments, gene therapy agents, photo-therapeutic agents,contrast agents, infusion media and combinations thereof. This isaccomplished by having ports or apertures 23 that are fluidly coupled toone or more lumens 72 coupled to lumens 13 in turn coupled to fluidreservoir 30 and/or fluid delivery device 28.

In an embodiment shown in FIG. 30 a, a conductivity enhancing solution27 can be infused into target tissue site 5′ including tissue mass 5″.The conductivity enhancing solution can be infused before, during, orafter the delivery of energy to the tissue site by the energy deliverydevice. The infusion of a conductivity enhancing solution 27 into thetarget tissue 5′ creates an infused tissue area 5 i that has anincreased electrical conductivity (versus un-infused tissue) so as toact as an enhanced electrode 40. During RF energy delivery, the currentdensities in enhanced electrode 40 are greatly lowered allowing thedelivery of greater amounts of RF power into electrode 40 and targettissue 5′ without impedance failures. In use, the infusion of the targettissue site with conductivity enhancing solution provides two importantbenefits: (i) faster ablation times; and (ii) the creation of largerlesions; both without impedance-related shut downs of the RF powersupply. This is due to the fact that the conductivity enhancing solutionreduces current densities and prevents desiccation of tissue adjacentthe electrode that would otherwise result in increases in tissueimpedance. A preferred example of a conductivity enhancing solution is ahypertonic saline solution. Other examples include halide saltsolutions, colloidal-ferro solutions, and colloidal-silver solutions.The conductivity of enhanced electrode 40 can be increased by control ofthe rate and amount of infusion and the use of solutions with greaterconcentrations of electrolytes (e.g. saline) and hence greaterconductivity. In various embodiments, the use of conductivity enhancingsolution 27 allows the delivery of up to 2000 watts of power into thetissue site impedance shut down, with specific embodiments of 50, 100,150, 250, 500, 1000 and 1500 watts achieved by varying the flow, amountand concentration of infusion solution 27. The infusion of solution 27can be continuous, pulsed or combinations thereof and can be controlledby a feedback control system described herein. In a specific embodiment,a bolus of infusion solution 27 is delivered prior to energy deliveryfollowed by a continuous delivery initiated before or during energydelivery with energy delivery device 18 or other means.

In an alternative embodiment, conductivity enhancing fluid 27 isinjected by electrically non conductive needles or infusion members 18nci (which include lumens 72 and apertures 23) coupled to advancementmember 16 and/or housing 12. Members 18 nci can be coupled to a fluiddelivery device 12 fdd positionable within housing 12. Fluid 27 inmembers 18 nci is electrically coupled to an RF or other power source 20via a conductor or electrode 18 c that is positioned within lumens 72and 13 and electrically coupled to power source 20. Members 18 nci areconfigured to infuse a fluid 27 into target tissue 5′ to define a tissueinfusion tissue volume 5 i. Electrically non-conductive infusion member18 nci can be fabricated from a variety of polymers known in the artincluding thermoset and rigid polymers such as ABS, acrylic andpolycarbonate. Alternatively member 18 nci can be fabricated frominsulated metal using insulation materials described herein.

In various embodiments, the conductivity of the tumor mass 5′ can beenhanced so as to preferentially increase the rate and total amount ofdelivery of energy to the tumor mass 5′ relative to healthy tissue. Thiscan be achieved by infusing conductivity enhancing solution 27 directlyinto the tumor mass 5′ through the use of a needle electrode 18 placedwithin the tumor mass only. In related embodiments solution 27 can beconfigured to remain or be preferentially absorbed or otherwise taken upby tumor mass 5″. This can be achieved by controlling one or more of theosmolality, viscosity and concentration of solution 27.

As shown in FIG. 30 b apertures 23 can be also configured to providecooling of electrodes 18 and surrounding tissue to prevent tissuedesiccation and the deposition of charred tissue on the surface ofelectrode 18 and in turn, prevent the subsequent development ofexcessive impedance at or near electrode 18. The cooling is accomplishedby both the use of a cooled solution to cool the electrodes by acombination of convection and conduction. The amount of cooling can becontrolled by control of one or more of the following parameters: (i)temperature of the cooling solution; (ii) flow rates of the coolingsolution; (iii) heat capacity (e.g. specific heat) of the coolingsolution; and (iv) combinations thereof. Examples of cooling solutionsinclude water, saline solution, ethanol, and combinations thereof. Otherembodiments can utilize a cooling fluid or gas 27 g that serves to coolelectrodes 18 by ebullient cooling or Joule-Thomson Effect cooling aswell as the mechanisms described above. Embodiments utilizingJoule-Thomson Effect cooling can have a nozzle-shaped aperture 23 n toprovide for expansion of a cooling fluid 27 g. Suitable cooling fluids27 g can include, but are not limited to, chilled water, freon, liquidCO₂, liquid nitrogen and other cryogenic gases.

Turning now to a discussion of power supplies and power delivery, whenpower supply 20 is a RF source it produces RF energy delivered to tissuethrough RF electrode 18. RF energy flowing through tissue causes heatingof the tissue due to absorption of the RF energy by the tissue and ohmicheating due to electrical resistance of the tissue. The heating causestissue temperature to rise sufficiently to cause cell injury and deathparticularly for temperatures in excess of 50-55° C. Increased amountsof power will resultant in higher temperature and greater magnitude ofcell death it is desirable to be able to deliver a range of RF powerlevels depending upon a variety of parameters include but not limited totumor size, tissue type, tumor location and amount of tumorvascularization. Accordingly in varying embodiments, RF power supply 20can be figured to deliver between 5 to 200 watts, preferably 5 to 100,and still more preferably 5 to 50 watts of electromagnetic energy is tothe electrodes of energy delivery device 18 without impeding out. Thiscan be accomplished through the use of cooling solutions and methodsdescribed herein as well as the use of power duty cycles to allow for acertain amount of thermal dissipation in and around electrodes 18.

Electrodes 18 are electromagnetically coupled to energy source 20. Thecoupling can be direct from energy source 20 to each electrode 18respectively, or indirect by using a collet, sleeve, connector, lemoconnectors, cable, wire and the like which couples one or moreelectrodes to energy source 20. Energy can also be beamed or transmittedto electrodes 18 using RF transmission or diathermy methods known in theart. Delivered energies can be in the range of 1 to 100,000 joules, morepreferably in the range 100 to 50000 joules, still more preferably inthe range of 100 to 5000 and still yet more preferably in the range 100to 1000 joules. Lower amounts of energy can be delivered for theablation of smaller structures such as nerves and small tumors withhigher amounts of energy for larger tumors. Also delivered energies canbe modified (by virtue of the signal modulation and frequency) to ablateor coagulate blood vessels vascularizing the tumor. This provides thebenefit of providing a higher degree of assurance of coagulating theblood supply of and to the tumor.

Turning to a discussion of sensors, sensor 22 can be selected to measuretemperature, impedance, pressure or other tissue property describedherein to permit real time monitoring, imaging and control of energydelivery or fluid delivery described herein. The use of one or moresensors 22 coupled to the housing 12, energy delivery surface 14, energydelivery devices 18 or handpiece 24 permits accurate measurement oftemperature at tissue site 5′ in order to determine the following: (i)the extent of cell necrosis; (ii) the amount of cell necrosis; (iii)whether or not further cell necrosis is needed; and (iv) the boundary orperiphery of the ablated tissue mass. Further, the use sensor 22 reducesnon-targeted tissue from being injured, destroyed or ablated.

Referring to back FIG. 2, one or more sensors 22 can be positioned atthe exterior surfaces of electrodes 18, at their distal ends 18 de, orintermediate sections. This allows monitoring of temperature, impedanceor other tissue property at various points within and outside of theinterior of tissue site 5′, such that a determination of one or more ofthe following can be made: (i) the periphery of the selectedtissue/tumor mass; (ii) the periphery of the developing ablation volume5 av; and (iii) a determination of when cell necrosis is complete. If atany time, sensor 22 determines that a desired cell necrosis temperatureis exceeded, then an appropriate feedback signal is received at powersource 20 coupled to energy delivery device 18 which then regulates theamount of electromagnetic energy delivered to electrodes 18 and 18′.This reduces damage to healthy tissue surrounding the targeted mass tobe ablated. Sensors 22 can be coupled to a multiplexer or otherswitching device (described herein) so as to integrate the signal fromone or more sensors 22 to obtain a composite picture of the sensedproperty for all or selected portions of the tumor surface area 5 b.

Sensor 22 can be of conventional design, including but not limited tothermal sensors, acoustical sensors, optical sensors, pH sensors, gassensors, flow sensors positional sensors and pressure/force sensors.Thermal sensors can include thermistors, thermocouples, resistive wires,optical sensors and the like. A suitable thermal sensor 22 includes a Ttype thermocouple with copper constantene, J type, E type, K type, fiberoptics, resistive wires, thermocouple IR detectors, and the like.Acoustical sensors can include ultrasound sensors includingpiezoelectric sensors which can be configured in an array. Pressure andforce sensors can include strain gauge sensors including silicon-basedstrain gauges contained in a miniaturized silicon chip including anASIC. Optical sensors can include photo-multipliers and micro-machinedoptical fibers. Gas sensors can include O₂ sensors such as Clarkelectrodes, CO₂ sensors and other electrochemical based sensors known inthe art. Flow/velocity sensors can include ultrasound sensors,electromagnetic sensors and aneometric sensors which can be configuredto detect both liquid and gaseous velocities and flow rates. Positionalsensors can include LVDT's, and Hall effect sensors. Other sensors whichcan be employed include impedance sensors, antibody-based sensors,biosensors (e.g. glucose) and chemical sensors. In various embodiments,one sensor can be configured to detect multiple parameters or one ormore sensors can be coupled together or arrayed so as to providecomposite information of a tissue site 5′. Pressure sensors can beselected and/or configured to detect pressure differentials less than 1mmHg and even less than 0.1 mmHg. In specific embodiments, pressuresensor 22 can be a micro-machined fiber optic sensor, a PSP-1 pressuresensor manufactured by Gaymar Industries Inc., (Orchard Park, N.Y.) or aMonolithic Integrated Pressure sensor made by the Fraunhofer-Institut(Duisburg, Germany). Suitable ultrasound sensors or transducers caninclude a Model 21362 imaging probe manufactured by the Hewlett PackardCompany, Palo Alto, Calif.

In other embodiments, at least a portion of sensors 22 can be pressureor force sensors positioned on or in housing 12, including tissuecontact surface 14, so as to be able to measure the force applied bysurface 14 onto tissue surface 5 s and into target tissue site 5′ tissuetumor mass 5″. Additionally, pressure/force sensors can provide anindication of the size of the ablation volume and/or the degree ofthermal injury due to the tissue shrinkage that occurs with the thermalcontraction and denaturization of collagen comprising tumor mass 5″ aswell as the shrinkage/coagulation of the vasculature within the tissuemass. Thus, a decreased pressure on surface 5 s can be an indication ofthe size of an ablation volume and/or the completeness of ablation of atumor mass. Also, an increase in pressure could provide an indication aswell, due to the development of steam and other gas pressure beneathtissue surface 5 s. Measurement of pressure changes occurring during RFor other thermal ablation treatment described herein can be combinedwith temperature measurements to provide a more robust indication ofcomplete tumor ablation and hence clinical endpoint. In one embodiment,an algorithm for determining an endpoint for ablation can include apolynomial equation and/or multi-variant analysis using both measurementof tissue temperature and tissue pressure as input parameters.

Pressure or force sensors 22 can be strain gauges, silicon basedpressure sensors, accelerometers, semiconductor gauge sensors, siliconstrain gauges, heat resistant silicon strain gauges, micro-machinedpressure sensors and the like. In an embodiment pressure sensor 22 canbe a flexible silicon strain gauge manufactured by the BF GoodrichAdvanced Micro Machines (Burnsville, Minn.).

Referring now to FIGS. 31-35, in various embodiments, housing 12 caninclude or be coupled to a graspable handle or handpiece 24. As shown inFIG. 31, handpiece 24 can include a grip portion 24 g and elongatedportion 24 e. Elongated portion 24 e can be attached at an angel 24 awith respect to the longitudinal axis 12 al of housing 12. Angle 24 canrange from 0 to 360° with specific embodiments of 15, 30, 45, 60, 90,120 and 180°. Also, all or portions of handpiece 24 can be integral tohousing 12.

The grip portion 24 g can have a variety of shapes and grips including,but not limited to, a screw driver grip, pistol grip and other gripsknown in the art. In various embodiments, elongated portion 24 e can bea wire-reinforced or metal-braided polymer shaft, a catheter, amulti-lumen catheter, port device (such as those made by the Heartport®Corp., Redwood City, Calif.), subcutaneous port or other medicalintroducing device known to those skilled in the art. In a specificembodiment, elongated portion 24 e is a trocar or a safety trocar andthe like. Also as described herein, elongated portion 24 e can beadapted to be coupled to or used in conjunction with various viewingdevices including, endoscopes, optical fibers, video imaging devices andthe like. Elongated portion 24 e can be constructed of a variety ofmetal grade metals known in the art including stainless steel such as304 or 304V stainless steel as well shape memory metal such as Nitinol.Elongated portion 24 e can also be constructed from rigid polymers suchas polycarbonate or ABS or resilient polymers including Pebax®,polyurethane, silicones HDPE, LDPE, polyesters and combinations thereof.

In various embodiments, handpiece 24 can include ports 24′ and actuators24″ shown in FIG. 32 a. Ports 24′ can be coupled to one or more lumens13 and can include fluid and gas ports/connectors and electrical,optical connectors. In various embodiments, ports 24′ can be configuredfor aspiration/vacuum (including the aspiration of tissue), and thedelivery of cooling, conductivity enhancing, electrolytic, irrigation,polymer and other fluids (both liquid and gas) described herein. Ports24′ can include but are not limited to luer fittings, valves (one-way,two-way), toughy-bourst connectors, swage fittings and other adaptorsand medical fittings known in the art. Ports 24′ can also includelemo-connectors, computer connectors (serial, parallel, DIN, etc) microconnectors and other electrical varieties well known to those skilled inthe art. Further, ports 24′ can include opto-electronic connectionswhich allow optical and electronic coupling of optical fibers and/orviewing scopes (such as an endoscope) to illuminating sources, eyepieces, video monitors and the like.

Actuators 24″ can include rocker switches, pivot bars, buttons, knobs,ratchets, cams, rack and pinion mechanisms, levers, slides and othermechanical actuators known in the art, all or portion of which can beindexed. These actuators can be configured to be mechanically,electro-mechanically, or optically coupled to pull wires, deflectionmechanisms and the like allowing selective control and steering ofintroducer 12. Also actuators 24″ can be configured such thatlongitudinal movement of actuators 24″ is translated to a combination oflateral or longitudinal movement of electrodes 18, contact surface 14,or forceps 24 p.

In an embodiment shown in FIG. 32 b, actuators 24″ can include apositioning fixture 24″p to control the penetration depth of electrodes18. Positioning fixture 24″p can include a rotatable positioningfixture, an indexed positioning fixture or a micro positioning fixtureall known in the art. Also the handpiece can include an electrodedeployment template 24 et with individual deployment actuators 24 da foreach electrode that enables or disables deployment of individualelectrode mechanically coupled to the electrode template.

As shown in FIG. 32 a, hand piece 24 can also be configured to becoupled to tissue aspiration/collection devices 26, fluid deliverydevices 28 (e.g. infusion pumps) fluid reservoirs (cooling,electrolytic, irrigation etc) 30 or power source 20 through the use ofports 24′. Tissue aspiration/collection devices 26 can include syringes,vacuum sources coupled to a filter or collection chamber/bag. Fluiddelivery device 28 can include medical infusion pumps, Harvard pumps,peristaltic pumps, syringes and the like.

In an embodiment shown in FIG. 33 elongated portion 24 e can include acurved portion 24 c positioned at the proximal or distal sections 24 epand 24 ed of elongate portion 243. Curved portion 24 c can have apreselected amount or arc of curvature 24 a ranging from 1 to 270° withspecific embodiments of 30, 60, 90, 120 and 180. In various embodiments,the length, shape and amount of curvature of handpiece 24 includingcurved portion 24 c are configured to allow the physician to positionthe housing 12 including tissue contacting surface 14 on the side(lateral) or back (posterior) surface of a target tissue site such asthe liver using an anterior or other approach. Curved portion 24 c caninclude a curvilinear, hyperbolic, parabolic or shaped curve orcombinations thereof.

Actuators 24″ can include rocker switches, pivot bars, buttons, knobs,ratchets, cams, rack and pinion mechanisms, levers, slides and othermechanical actuators known in the art, all or portions of which can beindexed. These actuators can be configured to be mechanically,electro-mechanically, or optically coupled to pull wires, deflectionmechanisms and the like allowing selective control and steering ofintroducer 12. Also actuators 24″ can be configured such thatlongitudinal movement of actuators 24″ is translated to a combination oflateral or longitudinal movement of electrodes 18, contact surface 14,or forceps 24 p.

In an embodiment shown in FIG. 34, handpiece 24 including elongatedportion 24 e can include a bendable or deflectable portion 24 b which isconfigured to allow portions of handpiece 24 to bend a selectable amountto allow the physician to position housing 12 on a selected surface of atarget organ 5 including the posterior and lateral surfaces of theorgan. In various embodiments, bendable portion 24 b can comprise anarticulated section using corrugated polymers known in the art or asection made from flexible or resilient materials including elastomerssuch as silicone or polyurethane, a coiled spring, a bendable wire, or awire reinforced catheter. In a preferred embodiment, bendable portion 24b comprises a braided resilient polymer tube known in the art. Bendableportion 24 b can be deflected using a number of deflection mechanismsknown in the art including pull wires 15 and the like. Alternatively,for embodiments having articulated bendable portions 24 b, thearticulations can have sufficient rigidity (e.g. bending force) tomaintain its shape once the physician has bent it into a desiredposition. This can be achieved through the use of metallic or steelarticulated sections 24 b having bending force ranging from 0.5 to 10lbs with specific embodiments of 1, 2.5 and 15 lbs of force.

In other embodiments, handpiece 24 can be configured to not onlyposition housing 12 adjacent the desired target tissue site, but also toshape or otherwise manipulate tissue contact surface 14 so as to atleast partially conform contact surface 14 and/or housing 12 to thecontour of the target tissue surface. This can be accomplished through avariety of mechanical means known in the surgical instrument arts. In anembodiment shown in FIG. 35, this can be accomplished by a pull wire 15(contained within elongated section 24 e) attached in two or more placesto a bendable tissue contact surface 14 and also to handpiece 24 so asto be controlled by actuators 24″. In a related embodiment, it can beaccomplished through the use of a forceps device 24 f attached to tissuesurface 14 and mechanically coupled to handpiece 24 (including actuator24″) by a connecting rod 15 cr or pull wire 15. Actuator 24″, connectingrod 15 cr or pull wire 15 can be so configured such that a longitudinalmovement of actuator 24 (with respect to axis 12 al) is translated intolateral or curved movement of surface 14 relative to a plane 14 p ofsurface 14. Forcep device 24 f can include forceps, curved forceps,hemostats, or any hinged or grasping device known in the surgical ormechanical arts.

The use of forcep device 24 f allows the physician to not only shape thecontact surface 14 to the tissue surface but also to apply a selectableamount of pressure to the tissue surface to do one or more of thefollowing: (i) stabilize the housing on the tissue surface; (ii) atleast partially immobilize the target tissue site; and (iii) at leastpartially stop the flow of blood to the target tissue through theapplication of direct pressure including onto a selected vessel orvasculature.

In use, coupled forcep device 24 f, provides the benefit of improvingthe contact of surface 14 to the tissue surface so as provide a moreprecise delivery of energy to the target tissue site and prevent damageto surrounding healthy structure. It also improves the ease and accuracyof the positioning and deployment of needles 18. Further, embodiments ofthe invention with coupled forcep device 24 f reduce the amount ofmanipulation of the liver or other target organ to position housing 12and needles 18 thus making associated ablation procedure less invasiveand less traumatic reducing the likelihood of morbidity and mortality aswell as reducing procedure time. This and related embodiments can beconfigured for endoscopic applications.

In use, a movable or bendable handpiece 24 and introducer solves theproblem of allowing the physician to atraumatically access difficult toreach portions of the liver including the posterior portion and lateralportions that are butting up against adjacent organs and structures.More importantly, the handpiece allows the physician to reach suchlocations without having to appreciably move or distend diseased (e.g.cirrhosed) or damaged portions of the liver that are subject to injuryincluding hemorrhage from such movement. In use embodiments having abendable handpiece serve to reduce the likelihood of injury during thepositioning of the device to the desired target tissue surface 5 s.Coating of the exterior of one or more of the handpiece, introducer andhousing with a lubricous coating known in the art also serves to makethe positioning of the housing, less atraumatic, faster and easier. Suchcoatings can include TEFLON and can be in the range of 0.0001 to 0.0003″in thickness.

Turning to a discussion of electrode deployment, in various embodimentselectrodes 18 can be controllably deployed from housing 12. Referring toFIGS. 36 a-36 b, electrodes 18 can have a non-deployed state in whichthey are contained within housing 12 and deployed state in which atleast a portion of the electrode is advanced out of the housing and intotissue. For embodiments having curved electrodes, electrodes 18 arepresprung or otherwise given memory using metallurgical methods known inthe art (such as mandrel shaping) such that their deployed stateelectrodes 18 assume a curved shape having at least one radius ofcurvature 18 r. Further the electrode 18 can be configured to assume agreater amount of curvature or otherwise be deflected or in response toa force exerted by tissue including tumor mass 5″ such that electrode 18has a changing direction of travel in tissue as the electrode isadvanced into tissue. In various embodiments, this can be achievedthrough the selection of the material properties of the electrodeincluding but not limited to elastic modulus, % elongation, yieldstrength, column strength, diameter, bending modulus, spring constant,degree of tapering and the like.

In a preferred embodiment, in their non deployed state electrodes 18 arecompletely contained or recessed within housing 12, particular tissuepenetrating distal end 18 de in the non deployed state and thensubsequently during electrode retraction. This configuration providesthe benefit of a safety feature to prevent accidental stick injury tomedical personnel and the patient. This is achieved by having electrodelength 18 l be less than housing length 12 l. In its fully deployedstate electrode has deployed portion 18 dp protruding distally out ofhousing 12 and into tissue and a non-deployed portion 18 ndp that iscontained in housing 12. In various embodiments, electrode 18 has adeployed length 18 dl in the range of 0.25 to 20 cm with specificembodiments of 1.5 cm, 2.5, 4, 5 and 10 cm in order to achieve apenetration depth 18 pd roughly corresponding to these amounts. In anembodiment, the non-deployed length can be in the range of 0.25 to 3 cm.At the same time, the housing 12 has sufficient length to allow completewithdrawal of electrodes 18 into the housing to prevent accidental stickinjury both to the patient and medical personnel during positioning andmanipulation of the housing and apparatus. Thus in various embodiments,the length of housing 12 can range of 0.5 cm to 9 cm with specificembodiments of 2.5, 5.0 and 7.5 cm. The actual lengths of electrode 18depends on the location of tissue site 5′ to be ablated, its distancefrom the site, its accessibility as well as whether or not the physicianchooses a open surgical procedure or a percutaneous, or other minimallyinvasive procedure.

By varying the depth of penetration, the pattern and number of deployedelectrodes, electrodes 18 can be selectably deployable from housing 12to create any desired geometric volume of cell necrosis. Accordingly,electrodes 18 can be configured to create a variety of differentgeometric ablation volumes or cell necrosis zones including but notlimited to spherical, semi-spherical, spheroid, triangular,semi-triangular, square, semi-square, rectangular, semi-rectangular,conical, semi-conical, quadrilateral, semi-quadrilateral,semi-quadrilateral, rhomboidal, semi-rhomboidal, trapezoidal,semi-trapezoidal, combinations of the preceding, geometries withnon-planar sections or sides, free-form and the like.

Referring to FIG. 37 in an embodiment, electrodes 18 can comprise anarray 18 a of deployable electrodes positioned in housing 12. Electrodearray 18 a can include a first, second and third electrode 18, 18″ and18′″ with other embodiments including 5, 7, 10, 15 and 20 electrodes.Electrodes 18′, 18″ and 18′″ can have tissue piercing distal ends 18 de′18 de″, and 18 de′″ respectively. Electrodes 18′, 18″ and 18′″ areselectably deployed with in straight fashion or with curvature fromapertures 14 a of tissue contact surface 14 to a selected tissue site5′. Tissue site 5′ can be any tissue mass and can be a tumor to beablated. Electrodes 18′, 18″ and 18′″ are selectably deployed to becontrollably positioned at a desired location relative to tissue site 5′that includes internal placement, external placement at a periphery oftissue site 5′ and at any desired location relative to tissue site 5′.The selectable deployment of electrodes 18′ 18″, and 18′″ to create adesired pattern of ablation or ablation volume 5 v can be achievedcontrolling one or more of the following parameters: (i) the amount ofadvancement of electrodes 18′ 18″, and 18′″ from housing 12; (ii) theindependent advancement of electrodes 18′ 18″, and 18′″ from housing 12;(iii) the lengths and/or sizes of energy delivery surfaces of electrodes18′, 18″ and 18′″; (iv) the variation in material properties (e.g.stiffness and column strength) used for electrodes 18′ 18″, and 18′″;and (v) variation of geometric configuration of electrodes 18′ 18″, and18′″ in their deployed states. Also, electrodes 18 can be deployedsimultaneously, in pairs, in sets and one at a time. Further, in variousembodiments any number of electrodes 18 can be coupled to housing 12 fordeployment.

In an embodiment electrodes 18′ and 18″ can have a radius of curvature18 r in their deployed stated, while electrode 18′″ remainssubstantially straight or has less curvature than electrodes 18′ and18′. As all three electrode are advanced into tissue the shape of theirperimeter 18 p or that of ablation volume 5 av stays substantially thesame (though it increases in size) independent of the amount oflongitudinal deployment of electrodes 18′ 18″, and 18′″ relative tohousing longitudinal axis 12 al. This scalability of ablation volumeshape is also shown in U.S. application Ser. No. 09/148,571, Filed Sep.4, 1998 which is incorporated by reference herein.

Referring to FIGS. 38 a and 38 b, in an embodiment of the apparatuselectrode 18 a can be configured as a substantially rectangular array 18ar having four or more electrodes 18. Housing 12 can also have asubstantially rectangular shape. The rectangular array 18 ar cancomprise one or more rows of electrodes 18 rw closely spaced, enablingthe physician to create a narrow rectangular and precise ablationvolume. Such spacing 18 lr of electrodes rows can be in the range of 1to 30 mms with specific embodiments of 10 and 20 mm. In use, embodimentsof a rectangular array 18 a would allow the physician to create a seriesof sectional ablation volumes which could be individually resectedand/or biopsied.

The tissue penetration depth of electrodes 18 can be controlled by avariety of means discussed herein including the use of a positioningfixture on the handpiece. Referring now to FIGS. 39-40, in variousembodiments penetration depth 18 pd can be controlled by a stop 33positioned on or in housing 12. Stop 33 can be a mechanical stopconfigured to limit a longitudinal or other movement of electrode 18.Stop 33 can positioned in or on the proximal or distal portion 12 p and12 d of housing 12. Further, stop 33 can be movably or fixedly coupledto housing 12 and can be integral to housing 12. In an embodiment shownin FIG. 39, stop 33 is a tubular sleeve of a set length that isconfigured to be coupled aperture 14 a and has diameter 33 d configuredto allow the advancement of electrode elongated section 18 es but stopor but up against proximal portion 18 p. The length 12 l of stop sleeve33 determines or limits electrode penetration depth 18 pd.

In related embodiment shown in FIG. 40, stop sleeve 33 is configured tobe movably adjustable (and hence penetration depth 18 pd as well) bybeing coupled to a lateral positioning arm member 33 pam that isconfigured to be slidably movable within a longitudinal slot 12 slt inhousing 12. Positioning arm member 12 pam can be fixed in particularlongitudinal position within the slot using a locking mechanism/member33 lm such as a locking nut or squeezable member. The exterior of slot12 slt can have depth/positional markings 12 dm that are pointed to byarm member 33 pam as the arm and coupled stop 33 are moved up and downin order to indicate the selected penetration depth 18 pd to the user.

In related embodiments penetration depth 18 pd as well electrodeposition can also be ascertained through the use of one or more sensors22 positioned on electrode 18, housing 12 or advancement member 16 onthe proximal or distal portions of each. Suitable positional sensorsthat can be employed include LVDTS and positional sensors known in theart. Such sensors 22 could also be configured to determine, fullelectrode deployment, partial deployment and full electrode retractionwith such conditions being indicated by a audio or visual signal on thedisplay of a coupled power supply 20 or computer/control system 338/329described herein. A hall effect switch or other switch sensor 22, couldbe used to determine full deployment and full retraction. This andrelated embodiments provides the benefit to the user of being able toreliably ascertain full deployment of the electrodes in tissue site 5′without having to resort to an imaging device such as fluoroscopy whichin turn reduces procedure time and exposure to ionizing radiation.Further, the embodiment of also provides the safety benefit ofindicating to the user when the electrodes are full retracted enablingapparatus 10 or housing 12 to be easily removed from the tissue surfacewithout the risk of puncture injury to the patient or associated medicalpersonnel.

Turning now to a discussion of the control of energy delivery byelectrodes 18, in various embodiments such control can be achieved viathe multiplexing of one or more electrodes 18. Referring to FIG. 41, inan embodiment one or more wires 18 h may be coupled to a multiplexingdevice 46 or other switching device known 46 in the art coupled to powersupply 20, allowing energy to be delivered to selected electrodes toachieve a desired spatial pattern of active electrodes or temporalpattern of or a combination of both. Spatial patterns can includecircular, semicircular, oval, crescent, rectangular and triangular.Temporal patterns can include pulsation, a square wave function, asinusoidal function and combinations thereof.

Referring to FIG. 42, in a related embodiment RF power source 20 canhave multiple independent channels 20 c, delivering separately modulatedpower to each RF electrode 18. This can be accomplished through the useof separate channels 20 c in a parallel connection or timesharing on thesame channel using a switching device or multiplexing device 46 and aserial connection or a combination of both. Such configurations reducespreferential heating that occurs when more energy is delivered to a zoneof greater conductivity and less heating occurs around RF electrodes 18which are placed into less conductive tissue. In use, a multichannel RFdevice 20 produces more uniform tissue ablations by solving the problemsof uneven or time varying amounts of tissue hydration or blood perfusionover the target tissue site 5″ which tend to cause uneven conductivityand tissue heating.

In various embodiments electrodes 18 can be operated in a monopolarmode, a bipolar mode, or a combination of both and can be switchablebetween the two. Referring now to FIG. 43, when electrodes 18/apparatus10 are operated in a monopolar mode, an indifferent electrode patch orground pad 18 g (also called a return electrode) is attached to thepatient's skin using known methods (e.g. use of a conductive gel) and isalso electrically coupled to power source 20 by a cable 20 gc or otherconnecting means. Ground pad 18 g serves to complete an electricalcircuit between one or more electrodes 18, the tissue site 5′ and thepower source 20. Ground pad 18 g can be a ground pad known in the artand can be made of a flexible material such as a resilient polymer andcan include a smooth, texturized or ridged surface. Ground pad 18 g hassufficient area to keep the current density at the point of contact withthe patient to low enough to prevent any appreciable heating of thepatient's skin. The ground pad can be an area in the range of 0.5 to 3square feet, with specific embodiments of 1, 2, and 2.5 square feet. Theuse of a texturized or ridged surface serves to increase the amount ofpad surface area in electrical contact with tissue and thus reducecurrent densities and reduce the risk of pad burns.

Referring now to FIGS. 44 a-44 c, in various embodiments, one or moreelectrodes 18 coupled to housing 12 can be operated in a bipolar mode.Bipolar mode includes at least two electrode including one electrodethat acts as a positive electrode 18 p and another electrode 18 n suchthat current flow from electrode 18 p to 18 n. Electrode array 18 a canbe configured with any number of positive or negative electrodes 18 pand 18 n as long as there is at least one of each. One configurationshown in FIG. 44 a includes a single positive and negative electrode 18p and 18 n. Other configuration can include multiple positive electrodes18 p and only one negative electrode 18 n or multiple positive andmultiple negative electrodes. Tissue heating is localized and occursadjacent both the positive and negative electrodes. The selection ofpositive and negative electrodes can be configured to control the areaof heating to match the tumor shape and also minimize heating ofsurrounding tissue. In one embodiment shown in FIG. 44 b, returnelectrode 18 n is located at the center or locus of circular or othergeometric pattern of positive electrode 18 p such that heating isconfined to the area bounded by the perimeter of the group of positiveelectrodes. In another embodiment shown in FIG. 44 c, the pattern ofpositive electrodes is arc shaped again with the return electrodelocated at the locus of the arc such that a pie shaped ablation volume 5av is produced. This ablation volume can be at least partly bounded bytissue surface 5 s or tissue proximate surface 5 s.

Referring to FIG. 45, all or portions of tissue surface 14 can be aconductive surface 14 con configured as the either the energy deliveryelectrode or the return electrode. This can be accomplished byfabricating surface 14 from conductive materials, coatings, or fromporous material configured to contain and or weep a conductive fluidfilm both configurations described herein. In various embodimentsconductive surface 14 con can be configured as a monopolar positiveelectrode, a monopolar return electrode or bipolar electrode. Switchingbetween these different modes can be accomplished through the use of aswitching device 46 such as a multiplexing device or programmablyswitching device coupled to one or more conductive surface 14 con,electrodes 18 and power supply 20.

Referring to FIG. 46, in a related embodiment conductive surface 14 concan comprise one or more conductive areas 14 cona which can each beindividually controlled to an on/off state using coupled to switchingdevice 46. The use of switching device 46 allows the user to dynamicallyincrease or decrease the conductive area 14 con of contact surface 14 todo one or more of the following: (i) adjust the area of conductivesurface 14 con as an energy delivery electrode or return electrode tocompensate for changes in tissue impedance; (ii) adjust the area oftissue heated; (iii) adjust the rate of tissue heating; and (iv) adjustthe area of area of conductive surface as a return electrode in order toprevent thermal damage to non-target tissue including coagulation ofblood vessels such as the hepatic vein.

When used as the positive electrode or the return electrode, conductivecontact surface 14 con can be configured to evenly deliver energy totissue surface 5 s in electrical contact with contact surface 14 and soas to generate a more uniform thermal profile within target tissuevolume 5″ and hence a more uniformly necrosed and ablated tissue volume.Similar benefits can be obtained for use of a conductive fluid film 14 fdescribed herein

Referring to FIG. 47, in related embodiments employing a conductivecontact surface 14 con as an electrode, one or more electrodes 18 can beselected as the positive electrode 18 p, using switching device 46 andso create a selectable composite vector(s) 18 v of current or energyinto target tissue 5′ having a selectable direction and magnitude. Theselection and configuration of electrodes 18 to produce a given vectorcan be controlled by logic resources 350 coupled to switching device 46which can be a multiplexing device. The vector 18 v can be in the volume5 ve defined by deployed electrodes 18, or the volume 5 vec deployedelectrodes 18 and conductive surface 14 con. In use, this approachallows the physician to more precisely control or titrate the deliveryof RF or others electromagnetic energy to yield higher current densitiesand hence temperatures in selected portions of the target tissue volumeand lower current densities in other selected areas. This configurationin turn provides benefit of providing a higher degree of cellnecrosis/ablation with a lower risk of tissue desiccation and excessiveimpedance build up.

Referring to FIG. 48, in another embodiment one or more electrodes 18and/or conductive surface 14 con can be configured to produce a phasedarray of RF electrode 18 pa to obtain a zone or area of constructivesignal interference 5 ci within target tissue volume 5′ under tissuesurface 5 s and hence an enhanced thermal effect with more rapid tissueheating and necrosis. Phased array embodiments can include use ofconductive surface 14 con as either a positive or electrode 18 p, 18 r.Electrodes 18 and/or conductive surface 14 con can be coupled to acontroller 339 described herein having logic resources (e.g. amicroprocessor) 350 that adjusts the feedback signal, with a gradientsearch or matrix inversion algorithm known in the art, to provide auniform electric field radiation into the target tissue site 5 ci.

Depending upon the location of the tumor it may be advantageous tooperate in a bipolar mode so as not to have the return electricalcurrent flow through a narrowed or small portion of the liver where thetissue impedance can be great enough to cause a temperature increasesufficient to coagulate or damage the hepatic vein or other hepaticvasculature. Accordingly, referring to FIGS. 49 a and 49 b, in anembodiment impedance measurement circuitry and/or controller/logicresources 338/350 (coupled to power source 20) can be configured todetermine if the return path impedance is sufficient to cause heatinganywhere along the return path and automatically switch into a bipolarmode either prior to energy delivery or once such impedance or resultingtemperature exceeds a preselected threshold. In a related embodiment,thermal, flow and coagulation sensors 22 can be positioned in thehepatic vasculature within target site 5′ or nearby tissue. Sensors 22can monitor both the temperature of the hepatic vasculature as well asmonitor blood flow rates there through the hepatic vasculature. Againsensors 22 are coupled to logic resources which switch from a monopolarto a bipolar mode, shut off or otherwise attenuate the delivery of powerto target site 5′ when: (i) the tissue temperature exceeds an absolutethreshold or a rate of increase; (ii) the blood flow rate falls below anabsolute threshold or a rate of decrease; or (iii) a combination ofitems (i) and (ii). In these and related embodiments, sensors 22 can bepositioned on electrode 18 or passive non energy delivering memberswhich can be positioned at varying distances from energy deliverydevices 18 so as to be to passively monitor tissue temperatures atselected distances from electrode 18. Sensors 22 can be electronicallycoupled to logic resource in turn coupled to power source 20. Suchresources can include microprocessors containing embedded modules orsoftware programs. Such microprocessors can include an Intel® Pentium®III chip or a PowerPC® chip manufactured by the Motorola Corporation.Such resource can also contained embedded control modules that includeprocess control algorithms known in the art such as PID algorithms. Theswitching between monopolar to bipolar modes can be achieved by the useof switching circuitry 20 s including multiplexer devices (including adensely packed wavelength multiplexor) coupled to one or more electrodes18 as wells as return electrode 18 r and tissue contact surface 14including conductive portions 14 con. Switching to bipolar mode alsoserves to keep RF induced heating closer to tissue surface 5 s thuspreventing the unwanted heating of deeper tissue containing healthytissue and/or thermally sensitive structures. Thus in use, embodimentshaving the ability to have feedback control to switch between monopolarand bipolar modes present the advantage of more refined and fastercontrol over the depth of tissue heating to prevent thermal injury ofunderlying healthy/sensitive tissue without having to reposition theelectrodes.

Referring to FIGS. 50 a, 50 b, and 51, in another embodiment of theinvention surface treatment apparatus 10 can comprise a collapsiblestrut apparatus 110 configured to be coupled to power source 20.Collapsible apparatus 110 can be configured to positionable within anendoscopic or a surgical introducing device 111 such as an endoscope,trocar and the like. Collapsible apparatus 110 has a collapsed or nondeployed position shown in 50 a and a deployed position shown in FIG. 50b. Collapsible apparatus 110 includes a central elongated or shaftmember 112 having a distal section 112 ds including a end 112 de. Aneedle electrode 118 n can be fixedly or movably attached to tip 112 de.Also shaft member 112 can include a lumen 1121 which can be configuredto allow the advancement of a rigid or a flexible advancement member116. Advancement member 116 can be flexible or rigid and can be guidewire, hypotube, or polymer shaft all having sufficient column strengthto advance a distally coupled needle into tissue. Advancement member 116can be coupled to a needle electrode 118 n to allow its advancement intotissue.

A movable proximal hub 120 is slidably positioned over shaft 112 and isconfigured to slides over distal section 112 ds and can be releasablylocked in position in position using a first locking device 120 l whichcan be a latch, locking nut or clamp known in the art. A distal hub 126is positioned over distal end 112 de and preferably is fixedly mounted.However the longitudinal position of hub 126 with respect to shaftlongitudinal axis 112 al can be adjusted using a second locking device126 l. Alternatively, in embodiment shown in FIG. 51, distal hub 126 canbe movable and proximal hub 120 can be fixed. Also, proximal hub 120 cancomprise an overtube 120 ot that is slidably positioned over shaft 112.Both of hubs 120 and 126 can be configured to be advanced and retractedby a coupled guidewire or other mechanical linkage known in the art. Inan embodiment one, or both of hubs 120 and 126 can include a flange 121f for 126 f that enables one or both hubs to be pushed (advanced) andpulled pack via means of either stiffened guide wires mechanicallycoupled (e.g. by welding) to either flange or a hollow advancement tubemember 130 that is coupled to or otherwise pushes up against eitherflange. In yet another embodiment either flange 121 f or 126 f can beconfigured to act as pneumatic or fluidic seal against the lumen of anoverlying introducer 111 such that either hub can be and retracted so asto deploy and retract electrodes 118 pneumatically or hydraulicallyusing an air or fluid pressure source 140 known in the medical devicearts. An example of air pressure source includes a tank of compressedgas and a fluid pressure source includes a syringe pump.

A plurality of strut members 122 are pivotally coupled to hub 120 usinga pivotal connector 121 which can be a hinged bracket, clamp or otherconnector known in the art. A second pivotal connector 123 is coupled tothe distal end of each strut member 122. A second strut member 124 ispivotally coupled to each connector 121 so as to comprise a plurality ofsecond strut members 124. The distal end 124 d of each second strutmember 124 is pivotally coupled to a third pivotal connector 125 in turncoupled to fixed hub 126.

A flexible guide tube member 128 is coupled to first strut member 122preferably at pivotal joint 121. In a specific embodiment, guide member128 is coupled to a channel or slot 124 c on or adjacent second strut124. Channel 124 c can be semicircular, sector or u-shaped to mate andhold guide 128 using an interference fit or adhesive bond. Guide tubemember 128 has a lumen 128 l for positioning and advancement of anelectrode 118 by a coupled advancement member 116 or other mechanicalmeans. Guide tube can 128 also be coupled to a tube bracket 128 b onstrut 124. When in the non-deployed state, guide tubes 128 are inproximity to shaft member 112 substantially parallel to axis 112 al.However, in the deployed state guide tubes 128 are pushed out a lateraldistance 128 ld from shaft 112 at channel 124 c by the deployment ofcoupled strut members 122 and 124 such that guide member now assumes acurved shape going from proximal hub 120 to its coupling at channel 124c. The curve can have one or more radii of curvature and can bes-shaped. However though curved in portions, guide tube 128 isconfigured to be substantially parallel to axis 112 al such thatelectrodes 118 exiting deployed guide tubes 128 are also substantiallyparallel to axis 112 al. This can be achieved by configuring or shapingthe distal end of guide tube 128 to curve at least partly inward in thenon-deployed state. This can be achieved using metalworking techniquesknown in the art including mandrel shaping, and also through the use ofshape memory materials.

Collectively hub 120, strut members 122, connectors 123, strut members124, connector 125, hub 126 and the distal portion 112 ds comprise anexpansion device 129 that is used to put apparatus 110 in its deployedstate. Apparatus 110 can be put into its deployed state by either thedistal advancement of hub 120, when hub 126 is fixed, or the proximalretraction of hub 126 when hub 120 is fixed. In the non deployed stateapparatus 110 including the coupled combination of shaft 112, strut 122,strut 124 and guide tube 128 has a cross sectional profile that can beadvanced through a standard sized endoscope or trocar (or other surgicalintroducer), including endoscopes having an internal diameter in therange of 0.1 to 1.0 inch with specific embodiments of 0.2, 0.5 and 0.8inches. In a preferred embodiment, apparatus 110 is configured to beadvanced through an introducing device 111 having an inner diameter of 1cm thus the maximum radial profile or diameter 110 d of apparatus in thenondeployed state is less than 1 cm, preferably by 0.002 or more to have0.001″ clearance on either side of apparatus 110 within the introducingdevice.

When in the deployed state, the linked struts 122 and 124 of expansiondevice 129 expand out laterally in a triangular shape to push guidetubes 128 out laterally in a substantially, triangular, diamond circularor oval pattern having shaft 120 as its center so as to enableelectrodes 118 contact tissue surface 5 s in such a pattern.

Turning now to a discussion of the materials of apparatus 110, shaftmember 112 and advancement member 116 can be fabricated from metals suchas 304 stainless steel or Nitinol and the like or a rigid polymer suchas a thermoset plastic, NYLON, ULTEM®, polyimide and the like. Also, allor portion of shaft 112 can have an insulative (both electrical andthermal) coating 113 which can include TEFLON®, polyimide, or silicone.Coating 113 can also be a lubricous coating such as TEFLON®, whichserves to reduce the friction of moving components and tissue in contactwith shaft 116. The interior of lumen 112 l as well as advancementmember 116 can also have coating 113. Similarly advancement member 116can have an insulative coating 113 which can be in the form of a movablesleeve 113 s so as to expose and/or create an energy delivery surface118 s of electrode 118. Sleeve 113 s can be mechanically linked to acoupled mechanical actuator 24″ on handpiece 24 which can be coupled toshaft member 112. Struts 122 and 124 can be rigid or flexible and can beconstructed from 304 or 304v stainless steel (for both rigid andflexible embodiments) and shape memory metals such as Nitinol forflexible embodiments. Pivotal joints 121, 123 and 125 can be fabricatedfrom machined or forged metals including 304 stainless steel andhardened tool steel. They can also include hinged, swaged, ball bearingor roller bearing pivot mechanisms known in the art. Guide tubes 128 caninclude rigid and flexible portions and can be fabricated from metalhypotubes which can be made from shape memory materials or high strengthand/or resilient polymers such as polyimide, PEEK™, HDPE, (includingradiated materials), PEBAX®, polyurethane and ULTEM®. Additionally, thedistal portions 128 d of guide tubes 128 can be more flexible thanproximal portions 128 p in order to assume a curved shape in thedeployed state and then reassume a substantially linear shape in thenon-deployed state. Accordingly the distal section 128 d can be madefrom flexible polymers, such as polyurethane and or can have a smallerdiameter versus proximal portions 128 p.

In an alternative embodiment, one or more of struts members 122 and 124can be configure as fluidic or hydraulic strut members and can beconfigured to be deployed via the application of fluidic or pneumaticpressure from a pressure source 140 described herein. This can beachieved by configuring one or more strut members 122 and 124 as hollow(single or multilumen) or porous tubular members or catheters fabricatedfrom resilient/inflatable polymers described herein.

Collapsible apparatus 110 and its methods of use provide the benefit ofallowing the physician to treat varying portions of a tumor mass 5″ aswell as multiple tumor masses without having to significantly repositionthe device using either open surgical procedures or endoscopic or otherminimally invasive methods. This is due to the ability of apparatus 110to have its electrode 118 be deployed at varying depths and varyinglocations without having to significantly reposition the apparatus.Referring now to FIG. 53, in an embodiment of the method of theinvention, the physician would position apparatus 110 at the targettissue site 5′ deploy the expansion device 129 to a selected firstdeployed diameter 129 d′ and deploy one or more electrode 118 throughguide tubes 128 and deliver RF energy to produce the desire ablationvolume 5 av. Having done so, the physician would withdrawal deployedelectrode 118 back into the guide tubes 128 and then expand or contractexpansion device 129 to a second diameter 129 dd″ and redeploy one ormore electrodes 118 and deliver RF energy to produce a second ablationvolume 5 av′ or expand the first volume 5 av. In this way the physiciancan avoid a critical anatomical structure 5 as positioned within atarget tissue site 5′ including within a tumor mass 5″ or between two ormore nearby tumor masses 5″. This method also provides the benefit ofproducing larger ablation volumes without the risk of impedance relatedshut downs, due to excessive tissue desiccation and impedance buildup inthe core of the ablation volume 5 avc which is continuously heated ifthe electrodes are not redeployed during the delivery of RF or otherenergy.

Referring now to FIGS. 53 a and 53 b, in an alternative embodimentexpansion device 129 can comprise an expandable balloon device known inthe art such as a dilatation balloon known in the art. Guide tubes 128can be distributed along a perimeter 129 p or a portion thereof ofballoon device 128. Balloon device 129 can be coupled to guide tubes 128using adhesive bonding and other polymer bonding methods known in theart (or alternatively balloon device 129 and guide tubes 128 can beintegrally formed). Balloon 129 is expanded to a selectable diameter toachieve a selected spacing or diameter 134 d of a geometric shape whoseperimeter is defined by deployed guide tubes 128. The shape or diameterof this shape in turn defines the collective shape or pattern 134 ofdeployed electrodes 118. The degree of inflation of balloon 129 can beused to match the diameter of deployed shape 134 to that of the tumormass 5″ or selected target tissue site 5′.

Balloon device 129 can be a balloon catheter or other inflatable deviceknown in the art made from balloon materials known in the medical devicearts including non-compliant materials such polyester, polyethylene(HDPE including radiated HDPE) latex and compliant material includingsilicones, polyurethane and latex. Balloon device 129 can be fabricatedusing balloon blowing methods known in the art including the use of moldblowing methods.

In an embodiment the maximum inflated diameter 129 d of balloon can beselectable and can include diameters in the range of 0.1 to 3 incheswith specific embodiments of 0.25, 0.5, 0.75 1, 1.5, 2 and 2.5 inchesThis can be achieved through the use of non-compliant balloon materialsblown in fixed balloon molds of set diameter. The maximum diameter canalso be achieved through the of E-beam irradiation (either before orafter balloon fabrication) to cross link the polymer chains of theballoon materials such as HDPE and so fix the maximum amount of theirexpansion.

Balloon 129 can have a variety of shapes including but not limited tospherical, oval, a tapered oval and cylindrical. In a specificembodiment balloon is a disk shaped (e.g. a short cylinder) balloon.Such balloons can be fabricated using disc shaped molds. They can alsobe fabricated by irradiating the top and bottom faces of the balloonmaking them hold a shape (e.g. non compliant due to cross linking) whilethe sides of the balloon that are joined to guide tubes 128 receive lessor no irradiation, are less cross linked and hence are free to expand tothe selected diameter.

In an alternative embodiment shown in FIG. 53 b a sizing or restrainingmember 131 can be disposed over balloon 129 and used to control themaximum inflated diameter 129 d of balloon 129 as well as the inflatedshape of balloon 129. The sizing member can be coupled to the proximaland distal portions of balloon 129 and can comprise a DACRON sheath orother collapsible yet substantially non-compliant material known in thebiomedical material arts including polyesters, PET and the like.

In various methods of use, expandable balloon 129 can be expanded indiameter (using an inflation device described herein) in incrementalamounts for the use of compliant material such as silicone or for noncompliant materials expandable balloon is expanded to final set diameterpreselected by the physician depending upon the size of the tissue mass5″ or desired ablation volume 5 av. To facilitate selection of differentdiameter balloons, in an embodiment the expandable balloon can bedetachably coupled to the distal portion 112 dp of shaft 112

Expandable balloon 129 can be expanded using any number of inflationdevices 133 and pressure sources known in the art including a automatedpumps and syringes pumps with coupled pressure gauges, including screwtype syringe pumps (handheld and automated) and computer controlledinflation devices that automatically adjust the pressure to produce aselected diameter using coupled position and sizing sensors. The ballooncan be inflated by means of an inflation lumen 112 l in shaft 112 whichis coupled to balloon 129. The balloon can also be configured to receivea liquid media including a radio-opaque contrast solution known in theart such that the physician can observe the amount of expansion underfluoroscopy or other imaging modality known in the art. In a relatedembodiment balloon 120 can be configured to receive an echogenicsolution such that balloon can visible under ultrasonagraphy.

In use, expandable balloon device 129 provides the advantage to thephysician of expansion device that can be readily advanced throughendoscopic and other minimally invasive introducing devices and at thesame time achieve a selectable and controlled size and shape for thepattern of deployed electrodes 118 such that this pattern is matched tothe size of the desired ablation volume 5 av to treat a selected tumormass 5″. More importantly, use of expandable balloon 129 in variousembodiments enables the creation of progressively larger ablationvolumes simply by expanding balloon 129 and subsequently deploying theelectrode and delivering ablative energy without having to repositionapparatus 110. This reduces both procedure time and reduces the risks ofcontamination of healthy tissue with cancerous cells from a tumor mass5′ by unnecessary movement of the apparatus 110 at the treatment sit e

The following discussion pertains particularly to the use of an RFenergy source and surface treatment apparatus 10 or 110 with controlsystems including feedback control systems, computer and microprocessorbased control systems. Referring now to FIGS. 55 and 56, in variousembodiments a feedback control system 329 can be cormected to energysource 320, sensors 324 and energy delivery devices 314 and 316. Forpurposes of this discussion, energy delivery devices 314 and 316 willnow be referred to as RF electrodes or antennas 314 and 316 and energysource 320 will now be an RF energy source. However it will beappreciated that all other energy delivery devices and sources discussedherein are equally applicable and devices similar to those associatedwith surface treatment ablation apparatus 10 can be utilized with laseroptical fibers, microwave devices and the like. The impedance ortemperature of the tissue, or of RF electrodes 314 and 316 is monitored,and the output power of energy source 320 adjusted accordingly. Thephysician can, if desired, override the closed or open loop system.

In an embodiment, feedback control system 329 receives temperature orimpedance data from sensors 324 and the amount of electromagnetic energyreceived by energy delivery devices 314 and 316 is modified from aninitial setting of ablation energy output, ablation time, temperature,and current density (the “Four Parameters”). Feedback control system 329can automatically change any of the Four Parameters individually or incombination. Feedback control system 329 can detect impedance ortemperature and change any of the Four Parameters. Feedback controlsystem 329 can include a multiplexer to multiplex different energydelivery devices/electrodes, a temperature detection circuit thatprovides a control signal representative of temperature or impedancedetected at one or more sensors 324. A microprocessor 339 can beconnected to the temperature control circuit.

The user of apparatus 10 can input an impedance value that correspondsto a setting position located at apparatus 10. Based on this value,along with measured impedance values, feedback control system 329determines an optimal power and time need in the delivery of RF energy.Temperature is also sensed for monitoring and feedback purposes.Temperature can be maintained to a certain level by having feedbackcontrol system 329 adjust the power output automatically to maintainthat level.

In another embodiment, feedback control system 329 determines an optimalpower and time for a baseline setting. Ablation volumes or lesions areformed at the baseline first. Larger lesions can be obtained byextending the time of ablation after a center core is formed at thebaseline. The completion of lesion creation can be checked by advancingenergy delivery device 316 from distal end 16 of introducer 12 to aposition corresponding to a desired lesion size and monitoring thetemperature at the periphery of the lesion such that a temperaturesufficient to produce a lesion is attained.

The closed loop system 329 can also utilize a controller 338 to monitorthe temperature, adjust the RF power, analyze the result, refeed theresult, and then modulate the power. More specifically, controller 338governs the power levels, cycles, and duration that the RF energy isdistributed to electrodes 314 and 316 to achieve and maintain powerlevels appropriate to achieve the desired treatment objectives andclinical endpoints. Controller 338 can also in tandem govern thedelivery of electrolytic, cooling fluid and, the removal of aspiratedtissue. Controller 338 can also in tandem monitor for excessiveimpedance at the tissue site and switch power sources 320 and electrodes314 and 316 from a monopolar mode to a bipolar mode or switch from useof ground pad electrode 18 g to conductive portions 14 con of tissuecontact surface 14. Controller 338 can be integral to or otherwisecoupled to power source 320. The controller 338 can be also be coupledto an input/output (I/O) device such as a keyboard, touchpad, PDA,microphone (coupled to speech recognition software resident incontroller 338 or other computer) and the like.

Referring now to FIG. 54, all or portions of feedback control system 329are illustrated. Current delivered through RF electrodes 314 and 316(also called primary and secondary RF electrodes/antennas 314 and 316)is measured by a current sensor 330. Voltage is measured by voltagesensor 332. Impedance and power are then calculated at power andimpedance calculation device 334. These values can then be displayed ata user interface and display 336. Signals representative of power andimpedance values are received by controller 338 which can be amicroprocessor 338.

A control signal is generated by controller 338 that is proportional tothe difference between an actual measured value, and a desired value.The control signal is used by power circuits 340 to adjust the poweroutput in an appropriate amount in order to maintain the desired powerdelivered at the respective primary and/or secondary antennas 314 and316. In a similar manner, temperatures detected at sensors 324 providefeedback for maintaining a selected power. The actual temperatures aremeasured at temperature measurement device 342, and the temperatures aredisplayed at user interface and display 336. A control signal isgenerated by controller 338 that is proportional to the differencebetween an actual measured temperature, and a desired temperature. Thecontrol signal is used by power circuits 340 to adjust the power outputin an appropriate amount in order to maintain the desired temperaturedelivered at the respective sensor 324. A multiplexer 346 can beincluded to measure current, voltage and temperature, at the numeroussensors 324 as will deliver and distribute energy between primaryelectrodes 314 and secondary electrodes 316.

Controller 338 can be a digital or analog controller, or a computer withembedded, resident or otherwise coupled software. In an embodiment,controller 338 can be a Pentium® family microprocessor manufacture bythe Intel® Corporation (Santa Clara, Calif.). When controller 338 is acomputer it can include a CPU coupled through a system bus. On thissystem can be a keyboard, a disk drive, or other non-volatile memorysystems, a display, and other peripherals, as are known in the art. Alsocoupled to the bus are a program memory and a data memory. In variousembodiments controller 338 can be coupled to imaging systems, includingbut not limited to ultrasound, CT scanners (including fast CT scannerssuch as those manufacture by the Imatron Corporation (South SanFrancisco, Calif.), X-ray, MRI, mammographic X-ray and the like.Further, direct visualization and tactile imaging can be utilized.

User interface and display 336 can include operator controls and adisplay. In an embodiment, user interface 336 can be a PDA device knownin the art such as a Palm® family computer manufactured by Palm®Computing (Santa Clara, Calif.). Interface 336 can be configured toallow the user to input control and processing variables, to enable thecontroller to generate appropriate command signals. Interface 336 canalso receives real time processing feedback information from one or moresensors 324 for processing by controller 338, to govern the delivery anddistribution of energy, fluid etc.

The output of current sensor 330 and voltage sensor 332 is used bycontroller 338 to maintain a selected power level at primary andsecondary antennas 314 and 316. The amount of RF energy deliveredcontrols the amount of power. A profile of power delivered can beincorporated in controller 338, and a preset amount of energy to bedelivered can also be profiled.

Circuitry, software and feedback to controller 338 result in processcontrol, and the maintenance of the selected power, and are used tochange, (i) the selected power, including RF, microwave, laser and thelike; (ii) the duty cycle (on-off and wattage); (iii) bipolar ormonopolar energy delivery; and (iv) infusion medium delivery, includingflow rate and pressure. These process variables are controlled andvaried, while maintaining the desired delivery of power independent ofchanges in voltage or current, based on temperatures monitored atsensors 324. A controller 338 can be incorporated into feedback controlsystem 329 to switch power on and off, as well as modulate the power.Also, with the use of sensor 324 and feedback control system 329, tissueadjacent to RF electrodes 314 and 316 can be maintained at a desiredtemperature for a selected period of time without causing a shut down ofthe power circuit to electrode 314 due to the development of excessiveelectrical impedance at electrode 314 or adjacent tissue. In relatedembodiment control system 329 can be used to determine and control thedeployment position and penetration depth of electrode 314.

Referring now to FIG. 55, current sensor 330 and voltage sensor 332 areconnected to the input of an analog amplifier 344. Analog amplifier 344can be a conventional differential amplifier circuit for use withsensors 324. The output of analog amplifier 344 is sequentiallyconnected by an analog multiplexer 346 to the input of A/D converter348. The output of analog amplifier 344 is a voltage which representsthe respective sensed temperatures. Digitized amplifier output voltagesare supplied by A/D converter 348 to a microprocessor 350.Microprocessor 350 may be Model No. 68HCII available from Motorola.However, it will be appreciated that any suitable microprocessor orgeneral purpose digital or analog computer can be used to calculateimpedance or temperature.

Microprocessor 350 sequentially receives and stores digitalrepresentations of impedance and temperature. Each digital valuereceived by microprocessor 350 corresponds to different temperatures andimpedances. Calculated power and impedance values can be indicated onuser interface and display 336. Alternatively, or in addition to thenumerical indication of power or impedance, calculated impedance andpower values can be compared by microprocessor 350 with power andimpedance limits. When the values exceed predetermined power orimpedance values, a warning can be given on user interface and display336, and additionally, the delivery of RF energy can be reduced,modified or interrupted. A control signal from microprocessor 350 canmodify the power level supplied by energy source 320 to RF electrodes314 and 316. In a similar manner, temperatures and positions detected atsensors 324 provide feedback for determining the extent and rate of (i)tissue hyperthermia; (ii) cell necrosis or ablation; and (iii) when aboundary of desired cell necrosis or ablation has reached the physicallocation of sensors 324.

CONCLUSION

It will be appreciated that the applicants have provided a novel anduseful apparatus and method for the treatment of tumors using surgicalor minimally invasive methods. The foregoing description of a preferredembodiment of the invention has been presented for purposes ofillustration and description. It is not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Embodiments of theinvention can be configured for the treatment of tumor and tissue massesat or beneath a tissue surface in a number of organs including but nolimited to the liver, breast, bone and lung. However, embodiments of theinvention are applicable to other organs and tissue as well. Obviously,many modifications and variations will be apparent to practitionersskilled in this art. Further, elements from one embodiment can bereadily recombined with elements from one or more other embodiments.Such combinations can form a number of embodiments within the scope ofthe invention. It is intended that the scope of the invention be definedby the following claims and their equivalents.

1. A method of controlling an ablation volume depth during surfacetreatment of a target tissue site, the method comprising: providing atissue surface treatment apparatus, the apparatus comprising a housinghaving a proximal end and a distal end including a substantially planartissue contacting surface having a plurality of apertures eachpositioned in the tissue contacting surface, the housing defining aninterior, an energy delivery device including a plurality of electrodes,each with a tissue penetrating distal end, the plurality of electrodesconfigured to be advanced from the housing interior through an apertureof the plurality of apertures and into a target tissue site to define anablation volume at least partly bounded by the tissue surface; anadvancement device being coupled to the energy delivery device, theadvancement device configured to selectively advance individualelectrodes of the plurality of electrodes from the housing interior to aselected deployment depth; positioning the tissue contact surface on atarget tissue surface; selectively advancing the plurality of electrodesto the selected deployment depth beneath a tissue surface while avoidinga critical structure; delivering ablative energy from the energydelivery device; creating an ablation volume at a controlled depth belowthe tissue surface responsive to the electrode advancement device; andminimizing injury to the critical structure responsive to the electrodedeployment depth.
 2. The method of claim 1, further comprising:controlling the deployment depth of the plurality of electrodes usingone of the advancement device, or a stop coupled to one of theadvancement device, the housing or the plurality of electrodes.
 3. Themethod of claim 1, wherein the plurality of electrodes includes a firstand a second electrode, the first and second electrodes beingindependently positionable, the method further comprising; positioningthe first electrode at a first selectable deployment depth; positioningthe second electrode at a second selectable deployment depth independentof the first depth; defining an ablation volume utilizing the first andthe second deployment depths.
 4. The method of claim 3, furthercomprising: positioning one of the first or the second electrodes toavoid or minimize injury to the critical structure.
 5. The method ofclaim 1, wherein the at least one of the plurality of electrodesincludes a sensor, the method further comprising: positioning at leastone of the plurality of electrodes responsive to an input from thesensor.
 6. The method of claim 1, wherein the apparatus is configured tobe advanceable within an introducer including a lumen, the methodfurther comprising: positioning the introducer proximate to the tissuesite; advancing the apparatus through the introducer lumen to the tissuesite.
 7. The method of claim 6, wherein at least a portion of theapparatus has a non-deployed state and a deployed state, at least aportion of the apparatus being configured to be advanceable through theintroducer lumen in the non-deployed state and positionable on thetissue surface in the deployed state, the method further comprising;advancing the apparatus through the introducer lumen in the nondeployedstate; deploying the apparatus to the deployed state to at leastpartially engage the tissue contacting surface with the tissue surface.8. The method of claim 1, wherein at least a portion of the housing ortissue contact surface is deflectable or conformable, the method furthercomprising: conforming or deflecting one of the housing or the contactsurface to at least partially correspond to a tissue surface contour. 9.The method of claim 8, wherein the apparatus includes a deflectionmechanism coupled to one of the tissue contact surface or the housing,the deflection mechanism including an actuating means configured toallow remote deflection of the housing or tissue contact surface, themethod further comprising: deflecting or bending the tissue contactsurface or housing utilizing the actuating means positioned externallyto the target tissue site or the tissue surface.
 10. A method of surfacetreatment of a target tissue site, the method comprising: providing atissue surface treatment apparatus, the apparatus comprising a housinghaving a proximal end and a substantially planar distal end having atleast one aperture positioned in the distal end, an expandable memberpositioned at the distal end of the housing and including a tissuecontacting surface, the expandable member having a non-deployed stateand an expanded or deployed state, and an energy delivery device, theenergy delivery device including a plurality of electrodes each with atissue penetrating distal end, the plurality of electrodes beingselectively advanceable through the at least one aperture and by orthrough the expandable member to an individual selected deployment depthwithin the target tissue site to define an ablation volume at leastpartly bounded by the tissue surface; positioning the apparatus at thetarget tissue site; deploying the expandable member to at leastpartially engage the target tissue surface; advancing the plurality ofelectrodes to the selected deployment depth beneath a tissue surfacewhile avoiding a critical structure; delivering ablative energy from theenergy delivery device; creating an ablation volume at a controlleddepth below the tissue surface responsive to the electrode deploymentdepth; and minimizing injury to the critical structure responsive to theelectrode deployment depth.
 11. The method of claim 10, furthercomprising: utilizing the expandable member to advance the plurality ofelectrodes.
 12. The method of claim 10, further comprising: utilizingthe expandable member to selectively control the deployment depth of theplurality of electrodes.
 13. The method of claim 10, further comprising:expanding the expandable member to at least partially stabilize orimmobilize the target tissue surface.
 14. The method of claim 10,further comprising: expanding the expandable member to at leastpartially stabilize or immobilize a tissue contacting surface of theexpandable member with respect to the tissue surface.
 15. The method ofclaim 10, further comprising: expanding the expandable member to apply asubstantially uniformly distributed force over an interface between theexpandable member and the target tissue surface.
 16. The method of claim15, further comprising: uniformly stabilizing or immobilizing the tissuesurface at an interface between the expandable member and the tissuesurface.
 17. The method of claim 10, wherein the apparatus is configuredto be advanceable within an introducer in the non-deployed state anddeployable from the introducer in the expanded state, the method furthercomprising: advancing the expandable member through the introducer lumenin the non-deployed state; positioning at least a portion of theexpandable member outside of a distal end of the introducer; expandingat least a portion of the expandable member to the deployed state. 18.The method of claim 10, wherein at least one of the plurality ofelectrodes includes a sensor, the method further comprising: positioningthe at least one electrode responsive to an input from the sensor. 19.The method of claim 10, wherein at least a portion of the expandablemember includes a fluid strut, the method further comprising: inflatingthe fluid strut to deploy the expansion device.
 20. A method ofcontrolling an ablation volume depth during surface treatment of atarget tissue site, the method comprising: providing a tissue surfacetreatment apparatus, the apparatus comprising a housing having aproximal end and a distal end having a substantially planar tissuecontacting surface configured to at least partially immobilize thetissue surface, the housing defining an interior; an energy deliverydevice positionable in the housing interior, the energy delivery deviceincluding a plurality of electrodes with a tissue penetrating distalend, the plurality of electrodes configured to be selectively advancedfrom the housing interior substantially normal to the plane of thetissue contacting surface to an individual selected deployment depth ina target tissue site to define an ablation volume at least partlybounded by the tissue surface; an advancement device being coupled tothe energy delivery device, the advancement device configured toselectively advance individual electrodes of the plurality of electrodesfrom the housing interior to a selected deployment depth; positioningthe tissue contacting surface on a target tissue surface; at leastpartially immobilizing the tissue surface utilizing the tissuecontacting surface; selectively advancing the plurality of electrodes tothe selected deployment depth beneath a tissue surface while avoiding acritical structure; delivering ablative energy from the energy deliverydevice; creating an ablation volume at a controlled depth below thetissue surface responsive to the electrode deployment depth; andminimizing injury to the critical structure responsive to the electrodedeployment depth.